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authorKartik K. Agaram <vc@akkartik.com>2017-06-09 11:29:15 -0700
committerKartik K. Agaram <vc@akkartik.com>2017-06-09 11:29:15 -0700
commit6d12a8c4ebe25527c92a934702e2628ce8c4bd4c (patch)
tree051825d9664a06fc3bc7085031fe62dfeb94c417
parentf53746f80145a184b5e4a6974175e2f92f49dcba (diff)
downloadmu-6d12a8c4ebe25527c92a934702e2628ce8c4bd4c.tar.gz
3902 - drop redundant redraw of recipe side on F4
This change is interesting because I only updated one test to gain confidence
that F4 will never redraw the recipe side. (Most of the changes are to
explicitly render-all before each scenario.)
-rw-r--r--edit/004-programming-environment.mu1
-rw-r--r--edit/005-sandbox.mu17
-rw-r--r--edit/006-sandbox-copy.mu4
-rw-r--r--edit/007-sandbox-delete.mu1
-rw-r--r--edit/008-sandbox-edit.mu3
-rw-r--r--edit/009-sandbox-test.mu1
-rw-r--r--edit/010-sandbox-trace.mu3
-rw-r--r--edit/011-errors.mu35
-rw-r--r--html/edit/004-programming-environment.mu.html197
-rw-r--r--html/edit/005-sandbox.mu.html2307
-rw-r--r--html/edit/006-sandbox-copy.mu.html750
-rw-r--r--html/edit/007-sandbox-delete.mu.html657
-rw-r--r--html/edit/008-sandbox-edit.mu.html615
-rw-r--r--html/edit/009-sandbox-test.mu.html359
-rw-r--r--html/edit/010-sandbox-trace.mu.html469
-rw-r--r--html/edit/011-errors.mu.html1337
-rw-r--r--sandbox/004-programming-environment.mu1
-rw-r--r--sandbox/005-sandbox.mu3
-rw-r--r--sandbox/006-sandbox-copy.mu3
-rw-r--r--sandbox/007-sandbox-delete.mu1
-rw-r--r--sandbox/008-sandbox-edit.mu3
-rw-r--r--sandbox/009-sandbox-test.mu1
-rw-r--r--sandbox/010-sandbox-trace.mu3
-rw-r--r--sandbox/011-errors.mu14
24 files changed, 3446 insertions, 3339 deletions
diff --git a/edit/004-programming-environment.mu b/edit/004-programming-environment.mu
index 55fd23f9..f0c8501e 100644
--- a/edit/004-programming-environment.mu
+++ b/edit/004-programming-environment.mu
@@ -451,6 +451,7 @@ def render-recipes screen:&:screen, env:&:environment, {render-editor: (recipe (
 def render-sandbox-side screen:&:screen, env:&:environment, {render-editor: (recipe (address screen) (address editor) -> number number (address screen) (address editor))} -> screen:&:screen, env:&:environment [
   local-scope
   load-ingredients
+  trace 11, [app], [render sandboxes]
   current-sandbox:&:editor <- get *env, current-sandbox:offset
   left:num <- get *current-sandbox, left:offset
   right:num <- get *current-sandbox, right:offset
diff --git a/edit/005-sandbox.mu b/edit/005-sandbox.mu
index 8db55206..caa3e6e6 100644
--- a/edit/005-sandbox.mu
+++ b/edit/005-sandbox.mu
@@ -47,6 +47,7 @@ scenario run-and-show-results [
   ]
   # sandbox editor contains an instruction without storing outputs
   env:&:environment <- new-programming-environment resources, screen, [divide-with-remainder 11, 3]
+  render-all screen, env, render
   # run the code in the editors
   assume-console [
     press F4
@@ -129,12 +130,17 @@ after <global-keypress> [
     break-unless do-run?
     screen <- update-status screen, [running...       ], 245/grey
     error?:bool <- run-sandboxes env, resources, screen
-    # F4 might update warnings and results on both sides
-    screen <- render-all screen, env, render
+    # we could just render-all, but we do some work to minimize the number of prints to screen
+    <render-recipe-errors-on-F4>
+    screen <- render-sandbox-side screen, env, render
     {
       break-if error?
       screen <- update-status screen, [                 ], 245/grey
     }
+    {
+      break-unless error?
+      <render-sandbox-errors-on-F4>
+    }
     screen <- update-cursor screen, recipes, current-sandbox, sandbox-in-focus?, env
     loop +next-event
   }
@@ -551,6 +557,8 @@ scenario run-updates-results [
   ]
   # sandbox editor contains an instruction without storing outputs
   env:&:environment <- new-programming-environment resources, screen, [foo]  # contents of sandbox editor
+  render-all screen, env, render
+  $clear-trace
   # run the code in the editors
   assume-console [
     press F4
@@ -568,6 +576,10 @@ scenario run-updates-results [
     .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .
     .                                                  ┊                                                 .
   ]
+  # no need to update editor
+  trace-should-not-contain [
+    app: render recipes
+  ]
   # make a change (incrementing one of the args to 'add'), then rerun
   assume-console [
     left-click 4, 28  # one past the value of the second arg
@@ -602,6 +614,7 @@ scenario run-instruction-manages-screen-per-sandbox [
   ]
   # sandbox editor contains an instruction
   env:&:environment <- new-programming-environment resources, screen, [print screen, 4]  # contents of sandbox editor
+  render-all screen, env, render
   # run the code in the editor
   assume-console [
     press F4
diff --git a/edit/006-sandbox-copy.mu b/edit/006-sandbox-copy.mu
index 4512afaf..ef9bed24 100644
--- a/edit/006-sandbox-copy.mu
+++ b/edit/006-sandbox-copy.mu
@@ -9,6 +9,7 @@ scenario copy-a-sandbox-to-editor [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 1, 1]  # contents of sandbox editor
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -69,6 +70,7 @@ scenario copy-a-sandbox-to-editor-2 [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 1, 1]  # contents of sandbox editor
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -222,6 +224,7 @@ scenario copy-fails-if-sandbox-editor-not-empty [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 1, 1]  # contents of sandbox editor
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -286,6 +289,7 @@ scenario copy-a-sandbox-to-recipe-side [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 1, 1]  # contents of sandbox editor
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
diff --git a/edit/007-sandbox-delete.mu b/edit/007-sandbox-delete.mu
index 4e10aa42..2db88964 100644
--- a/edit/007-sandbox-delete.mu
+++ b/edit/007-sandbox-delete.mu
@@ -7,6 +7,7 @@ scenario deleting-sandboxes [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, []
+  render-all screen, env, render
   # run a few commands
   assume-console [
     left-click 1, 75
diff --git a/edit/008-sandbox-edit.mu b/edit/008-sandbox-edit.mu
index 9a2b0e7a..eeb0cd69 100644
--- a/edit/008-sandbox-edit.mu
+++ b/edit/008-sandbox-edit.mu
@@ -8,6 +8,7 @@ scenario clicking-on-sandbox-edit-button-moves-it-to-editor [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 2, 2]
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -60,6 +61,7 @@ scenario clicking-on-sandbox-edit-button-moves-it-to-editor-2 [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 2, 2]
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -164,6 +166,7 @@ scenario sandbox-with-print-can-be-edited [
   ]
   # right editor contains a print instruction
   env:&:environment <- new-programming-environment resources, screen, [print screen, 4]
+  render-all screen, env, render
   # run the sandbox
   assume-console [
     press F4
diff --git a/edit/009-sandbox-test.mu b/edit/009-sandbox-test.mu
index cccee3e0..f0ec9cc9 100644
--- a/edit/009-sandbox-test.mu
+++ b/edit/009-sandbox-test.mu
@@ -13,6 +13,7 @@ scenario sandbox-click-on-result-toggles-color-to-green [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
diff --git a/edit/010-sandbox-trace.mu b/edit/010-sandbox-trace.mu
index 2c136587..2d681b8f 100644
--- a/edit/010-sandbox-trace.mu
+++ b/edit/010-sandbox-trace.mu
@@ -13,6 +13,7 @@ scenario sandbox-click-on-code-toggles-app-trace [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -87,6 +88,7 @@ scenario sandbox-shows-app-trace-and-result [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -131,6 +133,7 @@ scenario clicking-on-app-trace-does-nothing [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [stash 123456789]
+  render-all screen, env, render
   # create and expand the trace
   assume-console [
     press F4
diff --git a/edit/011-errors.mu b/edit/011-errors.mu
index 8c423106..cf12f1c1 100644
--- a/edit/011-errors.mu
+++ b/edit/011-errors.mu
@@ -23,20 +23,19 @@ def! update-recipes env:&:environment, resources:&:resources, screen:&:screen ->
   errors-found? <- copy 0/false
 ]
 
-before <render-components-end> [
-  trace 11, [app], [render status]
-  recipe-errors:text <- get *env, recipe-errors:offset
-  {
-    break-unless recipe-errors
-    update-status screen, [errors found     ], 1/red
-  }
-]
-
-before <render-recipe-components-end> [
+after <render-recipe-errors-on-F4> [
   {
     recipe-errors:text <- get *env, recipe-errors:offset
     break-unless recipe-errors
+    recipes:&:editor <- get *env, recipes:offset
+    left:num <- get *recipes, left:offset
+    right:num <- get *recipes, right:offset
+    row:num <- get *env, recipe-bottom:offset
     row, screen <- render-text screen, recipe-errors, left, right, 1/red, row
+    # draw dotted line after recipes
+    draw-horizontal screen, row, left, right, 9480/horizontal-dotted
+    row <- add row, 1
+    clear-screen-from screen, row, left, left, right
   }
 ]
 
@@ -61,7 +60,7 @@ before <run-sandboxes-end> [
   }
 ]
 
-before <render-components-end> [
+after <render-sandbox-errors-on-F4> [
   {
     break-if recipe-errors
     error-index:num <- get *env, error-index:offset
@@ -174,6 +173,7 @@ scenario run-updates-status-with-first-erroneous-sandbox [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, []
+  render-all screen, env, render
   assume-console [
     left-click 3, 80
     # create invalid sandbox 1
@@ -199,6 +199,7 @@ scenario run-updates-status-with-first-erroneous-sandbox-2 [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, []
+  render-all screen, env, render
   assume-console [
     left-click 3, 80
     # create invalid sandbox 2
@@ -227,6 +228,7 @@ scenario run-hides-errors-from-past-sandboxes [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [get foo, x:offset]  # invalid
+  render-all screen, env, render
   assume-console [
     press F4  # generate error
   ]
@@ -269,6 +271,7 @@ scenario run-updates-errors-for-shape-shifting-recipes [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo 2]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -322,6 +325,7 @@ scenario run-avoids-spurious-errors-on-reloading-shape-shifting-recipes [
   test-sandbox:text <- new [x:&:list:num <- copy 0
 to-text x]
   env:&:environment <- new-programming-environment resources, screen, test-sandbox
+  render-all screen, env, render
   # run it once
   assume-console [
     press F4
@@ -384,6 +388,7 @@ scenario run-shows-missing-type-errors [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -415,6 +420,7 @@ scenario run-shows-unbalanced-bracket-errors [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -446,6 +452,7 @@ scenario run-shows-get-on-non-container-errors [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -482,6 +489,7 @@ scenario run-shows-non-literal-get-argument-errors [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -518,6 +526,7 @@ scenario run-shows-errors-everytime [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -563,6 +572,7 @@ scenario run-instruction-and-print-errors [
   ]
   # sandbox editor contains an illegal instruction
   env:&:environment <- new-programming-environment resources, screen, [get 1234:num, foo:offset]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -625,6 +635,7 @@ scenario run-instruction-and-print-errors-only-once [
   ]
   # sandbox editor contains an illegal instruction
   env:&:environment <- new-programming-environment resources, screen, [get 1234:num, foo:offset]
+  render-all screen, env, render
   # run the code in the editors multiple times
   assume-console [
     press F4
@@ -663,6 +674,7 @@ scenario sandbox-can-handle-infinite-loop [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   # run the sandbox
   assume-console [
     press F4
@@ -701,6 +713,7 @@ scenario sandbox-with-errors-shows-trace [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo 4, 0]
+  render-all screen, env, render
   # run
   assume-console [
     press F4
diff --git a/html/edit/004-programming-environment.mu.html b/html/edit/004-programming-environment.mu.html
index 72593aa7..16d0d6f7 100644
--- a/html/edit/004-programming-environment.mu.html
+++ b/html/edit/004-programming-environment.mu.html
@@ -146,7 +146,7 @@ if ('onhashchange' in window) {
 <span id="L83" class="LineNr"> 83 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> _ <span class="Special">&lt;-</span> <a href='002-typing.mu.html#L50'>move-cursor-in-editor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, t
 <span id="L84" class="LineNr"> 84 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> sandbox-in-focus?:bool <span class="Special">&lt;-</span> <a href='002-typing.mu.html#L50'>move-cursor-in-editor</a> <a href='../081print.mu.html#L4'>screen</a>, current-sandbox, t
 <span id="L85" class="LineNr"> 85 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox-in-focus?:offset</span>, sandbox-in-focus?
-<span id="L86" class="LineNr"> 86 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L86" class="LineNr"> 86 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
 <span id="L87" class="LineNr"> 87 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
 <span id="L88" class="LineNr"> 88 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
 <span id="L89" class="LineNr"> 89 </span>  <span class="Conceal">¦</span> <span class="Comment"># 'resize' event - redraw editor</span>
@@ -185,7 +185,7 @@ if ('onhashchange' in window) {
 <span id="L122" class="LineNr">122 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
 <span id="L123" class="LineNr">123 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">}</span>
 <span id="L124" class="LineNr">124 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L125" class="LineNr">125 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L125" class="LineNr">125 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
 <span id="L126" class="LineNr">126 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
 <span id="L127" class="LineNr">127 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
 <span id="L128" class="LineNr">128 </span>  <span class="Delimiter">}</span>
@@ -478,7 +478,7 @@ if ('onhashchange' in window) {
 <span id="L415" class="LineNr">415 </span>  trace<span class="Constant"> 11</span>, <span class="Constant">[app]</span>, <span class="Constant">[render divider]</span>
 <span id="L416" class="LineNr">416 </span>  divider:num, _ <span class="Special">&lt;-</span> divide-with-remainder width,<span class="Constant"> 2</span>
 <span id="L417" class="LineNr">417 </span>  height:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> <a href='../081print.mu.html#L4'>screen</a>
-<span id="L418" class="LineNr">418 </span>  <a href='004-programming-environment.mu.html#L500'>draw-vertical</a> <a href='../081print.mu.html#L4'>screen</a>, divider, <span class="Constant">1/top</span>, height, <span class="Constant">9482/vertical-dotted</span>
+<span id="L418" class="LineNr">418 </span>  <a href='004-programming-environment.mu.html#L501'>draw-vertical</a> <a href='../081print.mu.html#L4'>screen</a>, divider, <span class="Constant">1/top</span>, height, <span class="Constant">9482/vertical-dotted</span>
 <span id="L419" class="LineNr">419 </span>  <span class="Comment">#</span>
 <span id="L420" class="LineNr">420 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L432'>render-recipes</a> <a href='../081print.mu.html#L4'>screen</a>, env, render-editor
 <span id="L421" class="LineNr">421 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, render-editor
@@ -487,7 +487,7 @@ if ('onhashchange' in window) {
 <span id="L424" class="LineNr">424 </span>  recipes:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">recipes:offset</span>
 <span id="L425" class="LineNr">425 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
 <span id="L426" class="LineNr">426 </span>  sandbox-in-focus?:bool <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox-in-focus?:offset</span>
-<span id="L427" class="LineNr">427 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L427" class="LineNr">427 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
 <span id="L428" class="LineNr">428 </span>  <span class="Comment">#</span>
 <span id="L429" class="LineNr">429 </span>  <a href='../081print.mu.html#L499'>assert-no-scroll</a> <a href='../081print.mu.html#L4'>screen</a>, old-top-idx
 <span id="L430" class="LineNr">430 </span>]
@@ -514,100 +514,101 @@ if ('onhashchange' in window) {
 <span id="L451" class="LineNr">451 </span><span class="muRecipe">def</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, env:&amp;:environment, <span class="Delimiter">{</span>render-editor: (recipe (address screen) (address editor)<span class="muRecipe"> -&gt; </span>number number (address screen) (address editor))<span class="Delimiter">}</span><span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, env:&amp;:environment [
 <span id="L452" class="LineNr">452 </span>  <span class="Constant">local-scope</span>
 <span id="L453" class="LineNr">453 </span>  <span class="Constant">load-ingredients</span>
-<span id="L454" class="LineNr">454 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L455" class="LineNr">455 </span>  left:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
-<span id="L456" class="LineNr">456 </span>  right:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">right:offset</span>
-<span id="L457" class="LineNr">457 </span>  row:num, column:num, <a href='../081print.mu.html#L4'>screen</a>, current-sandbox <span class="Special">&lt;-</span> call render-editor, <a href='../081print.mu.html#L4'>screen</a>, current-sandbox
-<span id="L458" class="LineNr">458 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, right
-<span id="L459" class="LineNr">459 </span>  row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
-<span id="L460" class="LineNr">460 </span>  <span class="Comment"># draw solid line after code (you'll see why in later layers)</span>
-<span id="L461" class="LineNr">461 </span>  <a href='002-typing.mu.html#L1060'>draw-horizontal</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, right
-<span id="L462" class="LineNr">462 </span>  row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
-<span id="L463" class="LineNr">463 </span>  <a href='001-editor.mu.html#L207'>clear-screen-from</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, left, right
-<span id="L464" class="LineNr">464 </span>]
-<span id="L465" class="LineNr">465 </span>
-<span id="L466" class="LineNr">466 </span><span class="muRecipe">def</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, recipes:&amp;:editor, current-sandbox:&amp;:editor, sandbox-in-focus?:bool, env:&amp;:environment<span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
-<span id="L467" class="LineNr">467 </span>  <span class="Constant">local-scope</span>
-<span id="L468" class="LineNr">468 </span>  <span class="Constant">load-ingredients</span>
-<span id="L469" class="LineNr">469 </span><span class="Constant">  <a href='004-programming-environment.mu.html#L469'>&lt;update-cursor-special-cases&gt;</a></span>
-<span id="L470" class="LineNr">470 </span>  <span class="Delimiter">{</span>
-<span id="L471" class="LineNr">471 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> sandbox-in-focus?
-<span id="L472" class="LineNr">472 </span>  <span class="Conceal">¦</span> cursor-row:num <span class="Special">&lt;-</span> get *recipes, <span class="Constant">cursor-row:offset</span>
-<span id="L473" class="LineNr">473 </span>  <span class="Conceal">¦</span> cursor-column:num <span class="Special">&lt;-</span> get *recipes, <span class="Constant">cursor-column:offset</span>
-<span id="L474" class="LineNr">474 </span>  <span class="Delimiter">}</span>
-<span id="L475" class="LineNr">475 </span>  <span class="Delimiter">{</span>
-<span id="L476" class="LineNr">476 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-in-focus?
-<span id="L477" class="LineNr">477 </span>  <span class="Conceal">¦</span> cursor-row:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">cursor-row:offset</span>
-<span id="L478" class="LineNr">478 </span>  <span class="Conceal">¦</span> cursor-column:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">cursor-column:offset</span>
-<span id="L479" class="LineNr">479 </span>  <span class="Delimiter">}</span>
-<span id="L480" class="LineNr">480 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, cursor-row, cursor-column
-<span id="L481" class="LineNr">481 </span>]
-<span id="L482" class="LineNr">482 </span>
-<span id="L483" class="LineNr">483 </span><span class="Comment"># ctrl-n - switch focus</span>
-<span id="L484" class="LineNr">484 </span><span class="Comment"># todo: test this</span>
-<span id="L485" class="LineNr">485 </span>
-<span id="L486" class="LineNr">486 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L67'>&lt;global-type&gt;</a></span> [
-<span id="L487" class="LineNr">487 </span>  <span class="Delimiter">{</span>
-<span id="L488" class="LineNr">488 </span>  <span class="Conceal">¦</span> switch-side?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">14/ctrl-n</span>
-<span id="L489" class="LineNr">489 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> switch-side?
-<span id="L490" class="LineNr">490 </span>  <span class="Conceal">¦</span> sandbox-in-focus?:bool <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox-in-focus?:offset</span>
-<span id="L491" class="LineNr">491 </span>  <span class="Conceal">¦</span> sandbox-in-focus? <span class="Special">&lt;-</span> not sandbox-in-focus?
-<span id="L492" class="LineNr">492 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox-in-focus?:offset</span>, sandbox-in-focus?
-<span id="L493" class="LineNr">493 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L494" class="LineNr">494 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L495" class="LineNr">495 </span>  <span class="Delimiter">}</span>
-<span id="L496" class="LineNr">496 </span>]
-<span id="L497" class="LineNr">497 </span>
-<span id="L498" class="LineNr">498 </span><span class="SalientComment">## helpers</span>
-<span id="L499" class="LineNr">499 </span>
-<span id="L500" class="LineNr">500 </span><span class="muRecipe">def</span> <a href='004-programming-environment.mu.html#L500'>draw-vertical</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, col:num, y:num, bottom:num<span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
-<span id="L501" class="LineNr">501 </span>  <span class="Constant">local-scope</span>
-<span id="L502" class="LineNr">502 </span>  <span class="Constant">load-ingredients</span>
-<span id="L503" class="LineNr">503 </span>  style:char, style-found?:bool <span class="Special">&lt;-</span> <span class="Constant">next-ingredient</span>
-<span id="L504" class="LineNr">504 </span>  <span class="Delimiter">{</span>
-<span id="L505" class="LineNr">505 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> style-found?
-<span id="L506" class="LineNr">506 </span>  <span class="Conceal">¦</span> style <span class="Special">&lt;-</span> copy <span class="Constant">9474/vertical</span>
-<span id="L507" class="LineNr">507 </span>  <span class="Delimiter">}</span>
-<span id="L508" class="LineNr">508 </span>  color:num, color-found?:bool <span class="Special">&lt;-</span> <span class="Constant">next-ingredient</span>
-<span id="L509" class="LineNr">509 </span>  <span class="Delimiter">{</span>
-<span id="L510" class="LineNr">510 </span>  <span class="Conceal">¦</span> <span class="Comment"># default color to white</span>
-<span id="L511" class="LineNr">511 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> color-found?
-<span id="L512" class="LineNr">512 </span>  <span class="Conceal">¦</span> color <span class="Special">&lt;-</span> copy <span class="Constant">245/grey</span>
-<span id="L513" class="LineNr">513 </span>  <span class="Delimiter">}</span>
-<span id="L514" class="LineNr">514 </span>  <span class="Delimiter">{</span>
-<span id="L515" class="LineNr">515 </span>  <span class="Conceal">¦</span> continue?:bool <span class="Special">&lt;-</span> lesser-than y, bottom
-<span id="L516" class="LineNr">516 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> continue?
-<span id="L517" class="LineNr">517 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, y, col
-<span id="L518" class="LineNr">518 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, style, color
-<span id="L519" class="LineNr">519 </span>  <span class="Conceal">¦</span> y <span class="Special">&lt;-</span> add y,<span class="Constant"> 1</span>
-<span id="L520" class="LineNr">520 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L521" class="LineNr">521 </span>  <span class="Delimiter">}</span>
-<span id="L522" class="LineNr">522 </span>]
-<span id="L523" class="LineNr">523 </span>
-<span id="L524" class="LineNr">524 </span><span class="muScenario">scenario</span> backspace-over-text [
-<span id="L525" class="LineNr">525 </span>  <span class="Constant">local-scope</span>
-<span id="L526" class="LineNr">526 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L527" class="LineNr">527 </span>  assume-screen <span class="Constant">50/width</span>, <span class="Constant">15/height</span>
-<span id="L528" class="LineNr">528 </span>  <span class="Comment"># recipes.mu is empty</span>
-<span id="L529" class="LineNr">529 </span>  assume-resources [
-<span id="L530" class="LineNr">530 </span>  ]
-<span id="L531" class="LineNr">531 </span>  <span class="Comment"># sandbox editor contains an instruction without storing outputs</span>
-<span id="L532" class="LineNr">532 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L533" class="LineNr">533 </span>  <span class="Comment"># run the code in the editors</span>
-<span id="L534" class="LineNr">534 </span>  assume-console [
-<span id="L535" class="LineNr">535 </span>  <span class="Conceal">¦</span> type <span class="Constant">[a]</span>
-<span id="L536" class="LineNr">536 </span>  <span class="Conceal">¦</span> press backspace
-<span id="L537" class="LineNr">537 </span>  ]
-<span id="L538" class="LineNr">538 </span>  run [
-<span id="L539" class="LineNr">539 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L540" class="LineNr">540 </span>  <span class="Conceal">¦</span> 10:num/<span class="Special">raw</span> <span class="Special">&lt;-</span> get *screen, <span class="Constant">cursor-row:offset</span>
-<span id="L541" class="LineNr">541 </span>  <span class="Conceal">¦</span> 11:num/<span class="Special">raw</span> <span class="Special">&lt;-</span> get *screen, <span class="Constant">cursor-column:offset</span>
-<span id="L542" class="LineNr">542 </span>  ]
-<span id="L543" class="LineNr">543 </span>  memory-should-contain [
-<span id="L544" class="LineNr">544 </span>  <span class="Conceal">¦</span><span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>
-<span id="L545" class="LineNr">545 </span>  <span class="Conceal">¦</span><span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>
-<span id="L546" class="LineNr">546 </span>  ]
-<span id="L547" class="LineNr">547 </span>]
+<span id="L454" class="LineNr">454 </span>  trace<span class="Constant"> 11</span>, <span class="Constant">[app]</span>, <span class="Constant">[render sandboxes]</span>
+<span id="L455" class="LineNr">455 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L456" class="LineNr">456 </span>  left:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
+<span id="L457" class="LineNr">457 </span>  right:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">right:offset</span>
+<span id="L458" class="LineNr">458 </span>  row:num, column:num, <a href='../081print.mu.html#L4'>screen</a>, current-sandbox <span class="Special">&lt;-</span> call render-editor, <a href='../081print.mu.html#L4'>screen</a>, current-sandbox
+<span id="L459" class="LineNr">459 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, right
+<span id="L460" class="LineNr">460 </span>  row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L461" class="LineNr">461 </span>  <span class="Comment"># draw solid line after code (you'll see why in later layers)</span>
+<span id="L462" class="LineNr">462 </span>  <a href='002-typing.mu.html#L1060'>draw-horizontal</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, right
+<span id="L463" class="LineNr">463 </span>  row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L464" class="LineNr">464 </span>  <a href='001-editor.mu.html#L207'>clear-screen-from</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, left, right
+<span id="L465" class="LineNr">465 </span>]
+<span id="L466" class="LineNr">466 </span>
+<span id="L467" class="LineNr">467 </span><span class="muRecipe">def</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, recipes:&amp;:editor, current-sandbox:&amp;:editor, sandbox-in-focus?:bool, env:&amp;:environment<span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
+<span id="L468" class="LineNr">468 </span>  <span class="Constant">local-scope</span>
+<span id="L469" class="LineNr">469 </span>  <span class="Constant">load-ingredients</span>
+<span id="L470" class="LineNr">470 </span><span class="Constant">  <a href='004-programming-environment.mu.html#L470'>&lt;update-cursor-special-cases&gt;</a></span>
+<span id="L471" class="LineNr">471 </span>  <span class="Delimiter">{</span>
+<span id="L472" class="LineNr">472 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> sandbox-in-focus?
+<span id="L473" class="LineNr">473 </span>  <span class="Conceal">¦</span> cursor-row:num <span class="Special">&lt;-</span> get *recipes, <span class="Constant">cursor-row:offset</span>
+<span id="L474" class="LineNr">474 </span>  <span class="Conceal">¦</span> cursor-column:num <span class="Special">&lt;-</span> get *recipes, <span class="Constant">cursor-column:offset</span>
+<span id="L475" class="LineNr">475 </span>  <span class="Delimiter">}</span>
+<span id="L476" class="LineNr">476 </span>  <span class="Delimiter">{</span>
+<span id="L477" class="LineNr">477 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-in-focus?
+<span id="L478" class="LineNr">478 </span>  <span class="Conceal">¦</span> cursor-row:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">cursor-row:offset</span>
+<span id="L479" class="LineNr">479 </span>  <span class="Conceal">¦</span> cursor-column:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">cursor-column:offset</span>
+<span id="L480" class="LineNr">480 </span>  <span class="Delimiter">}</span>
+<span id="L481" class="LineNr">481 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, cursor-row, cursor-column
+<span id="L482" class="LineNr">482 </span>]
+<span id="L483" class="LineNr">483 </span>
+<span id="L484" class="LineNr">484 </span><span class="Comment"># ctrl-n - switch focus</span>
+<span id="L485" class="LineNr">485 </span><span class="Comment"># todo: test this</span>
+<span id="L486" class="LineNr">486 </span>
+<span id="L487" class="LineNr">487 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L67'>&lt;global-type&gt;</a></span> [
+<span id="L488" class="LineNr">488 </span>  <span class="Delimiter">{</span>
+<span id="L489" class="LineNr">489 </span>  <span class="Conceal">¦</span> switch-side?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">14/ctrl-n</span>
+<span id="L490" class="LineNr">490 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> switch-side?
+<span id="L491" class="LineNr">491 </span>  <span class="Conceal">¦</span> sandbox-in-focus?:bool <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox-in-focus?:offset</span>
+<span id="L492" class="LineNr">492 </span>  <span class="Conceal">¦</span> sandbox-in-focus? <span class="Special">&lt;-</span> not sandbox-in-focus?
+<span id="L493" class="LineNr">493 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox-in-focus?:offset</span>, sandbox-in-focus?
+<span id="L494" class="LineNr">494 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L495" class="LineNr">495 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L496" class="LineNr">496 </span>  <span class="Delimiter">}</span>
+<span id="L497" class="LineNr">497 </span>]
+<span id="L498" class="LineNr">498 </span>
+<span id="L499" class="LineNr">499 </span><span class="SalientComment">## helpers</span>
+<span id="L500" class="LineNr">500 </span>
+<span id="L501" class="LineNr">501 </span><span class="muRecipe">def</span> <a href='004-programming-environment.mu.html#L501'>draw-vertical</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, col:num, y:num, bottom:num<span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
+<span id="L502" class="LineNr">502 </span>  <span class="Constant">local-scope</span>
+<span id="L503" class="LineNr">503 </span>  <span class="Constant">load-ingredients</span>
+<span id="L504" class="LineNr">504 </span>  style:char, style-found?:bool <span class="Special">&lt;-</span> <span class="Constant">next-ingredient</span>
+<span id="L505" class="LineNr">505 </span>  <span class="Delimiter">{</span>
+<span id="L506" class="LineNr">506 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> style-found?
+<span id="L507" class="LineNr">507 </span>  <span class="Conceal">¦</span> style <span class="Special">&lt;-</span> copy <span class="Constant">9474/vertical</span>
+<span id="L508" class="LineNr">508 </span>  <span class="Delimiter">}</span>
+<span id="L509" class="LineNr">509 </span>  color:num, color-found?:bool <span class="Special">&lt;-</span> <span class="Constant">next-ingredient</span>
+<span id="L510" class="LineNr">510 </span>  <span class="Delimiter">{</span>
+<span id="L511" class="LineNr">511 </span>  <span class="Conceal">¦</span> <span class="Comment"># default color to white</span>
+<span id="L512" class="LineNr">512 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> color-found?
+<span id="L513" class="LineNr">513 </span>  <span class="Conceal">¦</span> color <span class="Special">&lt;-</span> copy <span class="Constant">245/grey</span>
+<span id="L514" class="LineNr">514 </span>  <span class="Delimiter">}</span>
+<span id="L515" class="LineNr">515 </span>  <span class="Delimiter">{</span>
+<span id="L516" class="LineNr">516 </span>  <span class="Conceal">¦</span> continue?:bool <span class="Special">&lt;-</span> lesser-than y, bottom
+<span id="L517" class="LineNr">517 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> continue?
+<span id="L518" class="LineNr">518 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, y, col
+<span id="L519" class="LineNr">519 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, style, color
+<span id="L520" class="LineNr">520 </span>  <span class="Conceal">¦</span> y <span class="Special">&lt;-</span> add y,<span class="Constant"> 1</span>
+<span id="L521" class="LineNr">521 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L522" class="LineNr">522 </span>  <span class="Delimiter">}</span>
+<span id="L523" class="LineNr">523 </span>]
+<span id="L524" class="LineNr">524 </span>
+<span id="L525" class="LineNr">525 </span><span class="muScenario">scenario</span> backspace-over-text [
+<span id="L526" class="LineNr">526 </span>  <span class="Constant">local-scope</span>
+<span id="L527" class="LineNr">527 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L528" class="LineNr">528 </span>  assume-screen <span class="Constant">50/width</span>, <span class="Constant">15/height</span>
+<span id="L529" class="LineNr">529 </span>  <span class="Comment"># recipes.mu is empty</span>
+<span id="L530" class="LineNr">530 </span>  assume-resources [
+<span id="L531" class="LineNr">531 </span>  ]
+<span id="L532" class="LineNr">532 </span>  <span class="Comment"># sandbox editor contains an instruction without storing outputs</span>
+<span id="L533" class="LineNr">533 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L534" class="LineNr">534 </span>  <span class="Comment"># run the code in the editors</span>
+<span id="L535" class="LineNr">535 </span>  assume-console [
+<span id="L536" class="LineNr">536 </span>  <span class="Conceal">¦</span> type <span class="Constant">[a]</span>
+<span id="L537" class="LineNr">537 </span>  <span class="Conceal">¦</span> press backspace
+<span id="L538" class="LineNr">538 </span>  ]
+<span id="L539" class="LineNr">539 </span>  run [
+<span id="L540" class="LineNr">540 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L541" class="LineNr">541 </span>  <span class="Conceal">¦</span> 10:num/<span class="Special">raw</span> <span class="Special">&lt;-</span> get *screen, <span class="Constant">cursor-row:offset</span>
+<span id="L542" class="LineNr">542 </span>  <span class="Conceal">¦</span> 11:num/<span class="Special">raw</span> <span class="Special">&lt;-</span> get *screen, <span class="Constant">cursor-column:offset</span>
+<span id="L543" class="LineNr">543 </span>  ]
+<span id="L544" class="LineNr">544 </span>  memory-should-contain [
+<span id="L545" class="LineNr">545 </span>  <span class="Conceal">¦</span><span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>
+<span id="L546" class="LineNr">546 </span>  <span class="Conceal">¦</span><span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>
+<span id="L547" class="LineNr">547 </span>  ]
+<span id="L548" class="LineNr">548 </span>]
 </pre>
 </body>
 </html>
diff --git a/html/edit/005-sandbox.mu.html b/html/edit/005-sandbox.mu.html
index ecdf7f7b..7556ffa3 100644
--- a/html/edit/005-sandbox.mu.html
+++ b/html/edit/005-sandbox.mu.html
@@ -75,7 +75,7 @@ if ('onhashchange' in window) {
 <span id="L12" class="LineNr">  12 </span>  open-console
 <span id="L13" class="LineNr">  13 </span>  <a href='../081print.mu.html#L33'>clear-screen</a> <span class="Constant">0/screen</span>  <span class="Comment"># non-scrolling app</span>
 <span id="L14" class="LineNr">  14 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <span class="Constant">0/filesystem</span>, <span class="Constant">0/screen</span>
-<span id="L15" class="LineNr">  15 </span>  env <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L438'>restore-sandboxes</a> env
+<span id="L15" class="LineNr">  15 </span>  env <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L444'>restore-sandboxes</a> env
 <span id="L16" class="LineNr">  16 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <span class="Constant">0/screen</span>, env, <a href='001-editor.mu.html#L107'>render</a>
 <span id="L17" class="LineNr">  17 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <span class="Constant">0/screen</span>, <span class="Constant">0/console</span>, env, <span class="Constant">0/filesystem</span>
 <span id="L18" class="LineNr">  18 </span>]
@@ -110,1189 +110,1202 @@ if ('onhashchange' in window) {
 <span id="L47" class="LineNr">  47 </span>  ]
 <span id="L48" class="LineNr">  48 </span>  <span class="Comment"># sandbox editor contains an instruction without storing outputs</span>
 <span id="L49" class="LineNr">  49 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[divide-with-remainder 11, 3]</span>
-<span id="L50" class="LineNr">  50 </span>  <span class="Comment"># run the code in the editors</span>
-<span id="L51" class="LineNr">  51 </span>  assume-console [
-<span id="L52" class="LineNr">  52 </span>  <span class="Conceal">¦</span> press F4
-<span id="L53" class="LineNr">  53 </span>  ]
-<span id="L54" class="LineNr">  54 </span>  run [
-<span id="L55" class="LineNr">  55 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L56" class="LineNr">  56 </span>  ]
-<span id="L57" class="LineNr">  57 </span>  <span class="Comment"># check that screen prints the results</span>
-<span id="L58" class="LineNr">  58 </span>  screen-should-contain [
-<span id="L59" class="LineNr">  59 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L60" class="LineNr">  60 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L61" class="LineNr">  61 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L62" class="LineNr">  62 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L63" class="LineNr">  63 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎divide-with-remainder 11, 3                      .</span>
-<span id="L64" class="LineNr">  64 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎3                                                .</span>
-<span id="L65" class="LineNr">  65 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L66" class="LineNr">  66 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L67" class="LineNr">  67 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L68" class="LineNr">  68 </span>  ]
-<span id="L69" class="LineNr">  69 </span>  screen-should-contain-in-color <span class="Constant">7/white</span>, [
-<span id="L70" class="LineNr">  70 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L50" class="LineNr">  50 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L51" class="LineNr">  51 </span>  <span class="Comment"># run the code in the editors</span>
+<span id="L52" class="LineNr">  52 </span>  assume-console [
+<span id="L53" class="LineNr">  53 </span>  <span class="Conceal">¦</span> press F4
+<span id="L54" class="LineNr">  54 </span>  ]
+<span id="L55" class="LineNr">  55 </span>  run [
+<span id="L56" class="LineNr">  56 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L57" class="LineNr">  57 </span>  ]
+<span id="L58" class="LineNr">  58 </span>  <span class="Comment"># check that screen prints the results</span>
+<span id="L59" class="LineNr">  59 </span>  screen-should-contain [
+<span id="L60" class="LineNr">  60 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L61" class="LineNr">  61 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L62" class="LineNr">  62 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L63" class="LineNr">  63 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L64" class="LineNr">  64 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎divide-with-remainder 11, 3                      .</span>
+<span id="L65" class="LineNr">  65 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎3                                                .</span>
+<span id="L66" class="LineNr">  66 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L67" class="LineNr">  67 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L68" class="LineNr">  68 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L69" class="LineNr">  69 </span>  ]
+<span id="L70" class="LineNr">  70 </span>  screen-should-contain-in-color <span class="Constant">7/white</span>, [
 <span id="L71" class="LineNr">  71 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L72" class="LineNr">  72 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L73" class="LineNr">  73 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L74" class="LineNr">  74 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   divide-with-remainder 11, 3                      .</span>
-<span id="L75" class="LineNr">  75 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L74" class="LineNr">  74 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L75" class="LineNr">  75 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   divide-with-remainder 11, 3                      .</span>
 <span id="L76" class="LineNr">  76 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L77" class="LineNr">  77 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L78" class="LineNr">  78 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L79" class="LineNr">  79 </span>  ]
-<span id="L80" class="LineNr">  80 </span>  screen-should-contain-in-color <span class="Constant">245/grey</span>, [
-<span id="L81" class="LineNr">  81 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L82" class="LineNr">  82 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L83" class="LineNr">  83 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L84" class="LineNr">  84 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L79" class="LineNr">  79 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L80" class="LineNr">  80 </span>  ]
+<span id="L81" class="LineNr">  81 </span>  screen-should-contain-in-color <span class="Constant">245/grey</span>, [
+<span id="L82" class="LineNr">  82 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L83" class="LineNr">  83 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L84" class="LineNr">  84 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
 <span id="L85" class="LineNr">  85 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L86" class="LineNr">  86 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎3                                                .</span>
-<span id="L87" class="LineNr">  87 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L88" class="LineNr">  88 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L89" class="LineNr">  89 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L90" class="LineNr">  90 </span>  ]
-<span id="L91" class="LineNr">  91 </span>  <span class="Comment"># sandbox menu in reverse video</span>
-<span id="L92" class="LineNr">  92 </span>  screen-should-contain-in-color <span class="Constant">232/black</span>, [
-<span id="L93" class="LineNr">  93 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L86" class="LineNr">  86 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L87" class="LineNr">  87 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎3                                                .</span>
+<span id="L88" class="LineNr">  88 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L89" class="LineNr">  89 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L90" class="LineNr">  90 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L91" class="LineNr">  91 </span>  ]
+<span id="L92" class="LineNr">  92 </span>  <span class="Comment"># sandbox menu in reverse video</span>
+<span id="L93" class="LineNr">  93 </span>  screen-should-contain-in-color <span class="Constant">232/black</span>, [
 <span id="L94" class="LineNr">  94 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L95" class="LineNr">  95 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L96" class="LineNr">  96 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   0   edit       copy       to recipe    delete    .</span>
-<span id="L97" class="LineNr">  97 </span>  ]
-<span id="L98" class="LineNr">  98 </span>  <span class="Comment"># run another command</span>
-<span id="L99" class="LineNr">  99 </span>  assume-console [
-<span id="L100" class="LineNr"> 100 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 1</span>,<span class="Constant"> 80</span>
-<span id="L101" class="LineNr"> 101 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L102" class="LineNr"> 102 </span>  <span class="Conceal">¦</span> press F4
-<span id="L103" class="LineNr"> 103 </span>  ]
-<span id="L104" class="LineNr"> 104 </span>  run [
-<span id="L105" class="LineNr"> 105 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L106" class="LineNr"> 106 </span>  ]
-<span id="L107" class="LineNr"> 107 </span>  <span class="Comment"># check that screen prints both sandboxes</span>
-<span id="L108" class="LineNr"> 108 </span>  screen-should-contain [
-<span id="L109" class="LineNr"> 109 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L110" class="LineNr"> 110 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L111" class="LineNr"> 111 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L112" class="LineNr"> 112 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L113" class="LineNr"> 113 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L114" class="LineNr"> 114 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L115" class="LineNr"> 115 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L116" class="LineNr"> 116 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L117" class="LineNr"> 117 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎divide-with-remainder 11, 3                      .</span>
-<span id="L118" class="LineNr"> 118 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎3                                                .</span>
-<span id="L119" class="LineNr"> 119 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L120" class="LineNr"> 120 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L121" class="LineNr"> 121 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L122" class="LineNr"> 122 </span>  ]
-<span id="L123" class="LineNr"> 123 </span>]
-<span id="L124" class="LineNr"> 124 </span>
-<span id="L125" class="LineNr"> 125 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L62'>&lt;global-keypress&gt;</a></span> [
-<span id="L126" class="LineNr"> 126 </span>  <span class="Comment"># F4? load all code and run all sandboxes.</span>
-<span id="L127" class="LineNr"> 127 </span>  <span class="Delimiter">{</span>
-<span id="L128" class="LineNr"> 128 </span>  <span class="Conceal">¦</span> do-run?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">65532/F4</span>
-<span id="L129" class="LineNr"> 129 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> do-run?
-<span id="L130" class="LineNr"> 130 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L213'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[running...       ]</span>, <span class="Constant">245/grey</span>
-<span id="L131" class="LineNr"> 131 </span>  <span class="Conceal">¦</span> error?:bool <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L143'>run-sandboxes</a> env, <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>
-<span id="L132" class="LineNr"> 132 </span>  <span class="Conceal">¦</span> <span class="Comment"># F4 might update warnings and results on both sides</span>
-<span id="L133" class="LineNr"> 133 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L134" class="LineNr"> 134 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L135" class="LineNr"> 135 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> error?
-<span id="L136" class="LineNr"> 136 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L213'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[                 ]</span>, <span class="Constant">245/grey</span>
-<span id="L137" class="LineNr"> 137 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L138" class="LineNr"> 138 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L139" class="LineNr"> 139 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L140" class="LineNr"> 140 </span>  <span class="Delimiter">}</span>
-<span id="L141" class="LineNr"> 141 </span>]
-<span id="L142" class="LineNr"> 142 </span>
-<span id="L143" class="LineNr"> 143 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L143'>run-sandboxes</a> env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a><span class="muRecipe"> -&gt; </span>errors-found?:bool, env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
-<span id="L144" class="LineNr"> 144 </span>  <span class="Constant">local-scope</span>
-<span id="L145" class="LineNr"> 145 </span>  <span class="Constant">load-ingredients</span>
-<span id="L146" class="LineNr"> 146 </span>  errors-found?:bool <span class="Special">&lt;-</span> update-recipes env, <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>
-<span id="L147" class="LineNr"> 147 </span>  <span class="muControl">jump-if</span> errors-found?, <span class="Constant">+return</span>
-<span id="L148" class="LineNr"> 148 </span>  <span class="Comment"># check contents of right editor (sandbox)</span>
-<span id="L149" class="LineNr"> 149 </span><span class="Constant">  <a href='005-sandbox.mu.html#L149'>&lt;run-sandboxes-begin&gt;</a></span>
-<span id="L150" class="LineNr"> 150 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L151" class="LineNr"> 151 </span>  <span class="Delimiter">{</span>
-<span id="L152" class="LineNr"> 152 </span>  <span class="Conceal">¦</span> sandbox-contents:text <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L630'>editor-contents</a> current-sandbox
-<span id="L153" class="LineNr"> 153 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-contents
-<span id="L154" class="LineNr"> 154 </span>  <span class="Conceal">¦</span> <span class="Comment"># if contents exist, first save them</span>
-<span id="L155" class="LineNr"> 155 </span>  <span class="Conceal">¦</span> <span class="Comment"># run them and turn them into a new sandbox</span>
-<span id="L156" class="LineNr"> 156 </span>  <span class="Conceal">¦</span> new-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> new <span class="Constant">sandbox:type</span>
-<span id="L157" class="LineNr"> 157 </span>  <span class="Conceal">¦</span> *new-sandbox <span class="Special">&lt;-</span> put *new-sandbox, <span class="Constant">data:offset</span>, sandbox-contents
-<span id="L158" class="LineNr"> 158 </span>  <span class="Conceal">¦</span> <span class="Comment"># push to head of sandbox list</span>
-<span id="L159" class="LineNr"> 159 </span>  <span class="Conceal">¦</span> dest:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L160" class="LineNr"> 160 </span>  <span class="Conceal">¦</span> *new-sandbox <span class="Special">&lt;-</span> put *new-sandbox, <span class="Constant">next-sandbox:offset</span>, dest
-<span id="L161" class="LineNr"> 161 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox:offset</span>, new-sandbox
-<span id="L162" class="LineNr"> 162 </span>  <span class="Conceal">¦</span> <span class="Comment"># update sandbox count</span>
-<span id="L163" class="LineNr"> 163 </span>  <span class="Conceal">¦</span> sandbox-count:num <span class="Special">&lt;-</span> get *env, <span class="Constant">number-of-sandboxes:offset</span>
-<span id="L164" class="LineNr"> 164 </span>  <span class="Conceal">¦</span> sandbox-count <span class="Special">&lt;-</span> add sandbox-count,<span class="Constant"> 1</span>
-<span id="L165" class="LineNr"> 165 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">number-of-sandboxes:offset</span>, sandbox-count
-<span id="L166" class="LineNr"> 166 </span>  <span class="Conceal">¦</span> <span class="Comment"># clear sandbox editor</span>
-<span id="L167" class="LineNr"> 167 </span>  <span class="Conceal">¦</span> init:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> push <span class="Constant">167/§</span>, <span class="Constant">0/tail</span>
-<span id="L168" class="LineNr"> 168 </span>  <span class="Conceal">¦</span> *current-sandbox <span class="Special">&lt;-</span> put *current-sandbox, <span class="Constant">data:offset</span>, init
-<span id="L169" class="LineNr"> 169 </span>  <span class="Conceal">¦</span> *current-sandbox <span class="Special">&lt;-</span> put *current-sandbox, <span class="Constant">top-of-screen:offset</span>, init
-<span id="L170" class="LineNr"> 170 </span>  <span class="Delimiter">}</span>
-<span id="L171" class="LineNr"> 171 </span>  <span class="Comment"># save all sandboxes before running, just in case we die when running</span>
-<span id="L172" class="LineNr"> 172 </span>  <a href='005-sandbox.mu.html#L220'>save-sandboxes</a> env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L173" class="LineNr"> 173 </span>  <span class="Comment"># run all sandboxes</span>
-<span id="L174" class="LineNr"> 174 </span>  curr:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L175" class="LineNr"> 175 </span>  idx:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
-<span id="L176" class="LineNr"> 176 </span>  <span class="Delimiter">{</span>
-<span id="L177" class="LineNr"> 177 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> curr
-<span id="L178" class="LineNr"> 178 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> update-sandbox curr, env, idx
-<span id="L179" class="LineNr"> 179 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> get *curr, <span class="Constant">next-sandbox:offset</span>
-<span id="L180" class="LineNr"> 180 </span>  <span class="Conceal">¦</span> idx <span class="Special">&lt;-</span> add idx,<span class="Constant"> 1</span>
-<span id="L181" class="LineNr"> 181 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L182" class="LineNr"> 182 </span>  <span class="Delimiter">}</span>
-<span id="L183" class="LineNr"> 183 </span><span class="Constant">  <a href='005-sandbox.mu.html#L183'>&lt;run-sandboxes-end&gt;</a></span>
-<span id="L184" class="LineNr"> 184 </span><span class="Constant">  +return</span>
-<span id="L185" class="LineNr"> 185 </span>  <span class="Delimiter">{</span>
-<span id="L186" class="LineNr"> 186 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> <a href='../088file.mu.html#L11'>resources</a>  <span class="Comment"># ignore this in tests</span>
-<span id="L187" class="LineNr"> 187 </span>  <span class="Conceal">¦</span> $system <span class="Constant">[./snapshot_lesson]</span>
+<span id="L96" class="LineNr">  96 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L97" class="LineNr">  97 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   0   edit       copy       to recipe    delete    .</span>
+<span id="L98" class="LineNr">  98 </span>  ]
+<span id="L99" class="LineNr">  99 </span>  <span class="Comment"># run another command</span>
+<span id="L100" class="LineNr"> 100 </span>  assume-console [
+<span id="L101" class="LineNr"> 101 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 1</span>,<span class="Constant"> 80</span>
+<span id="L102" class="LineNr"> 102 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L103" class="LineNr"> 103 </span>  <span class="Conceal">¦</span> press F4
+<span id="L104" class="LineNr"> 104 </span>  ]
+<span id="L105" class="LineNr"> 105 </span>  run [
+<span id="L106" class="LineNr"> 106 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L107" class="LineNr"> 107 </span>  ]
+<span id="L108" class="LineNr"> 108 </span>  <span class="Comment"># check that screen prints both sandboxes</span>
+<span id="L109" class="LineNr"> 109 </span>  screen-should-contain [
+<span id="L110" class="LineNr"> 110 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L111" class="LineNr"> 111 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L112" class="LineNr"> 112 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L113" class="LineNr"> 113 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L114" class="LineNr"> 114 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L115" class="LineNr"> 115 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L116" class="LineNr"> 116 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L117" class="LineNr"> 117 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L118" class="LineNr"> 118 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎divide-with-remainder 11, 3                      .</span>
+<span id="L119" class="LineNr"> 119 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎3                                                .</span>
+<span id="L120" class="LineNr"> 120 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L121" class="LineNr"> 121 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L122" class="LineNr"> 122 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L123" class="LineNr"> 123 </span>  ]
+<span id="L124" class="LineNr"> 124 </span>]
+<span id="L125" class="LineNr"> 125 </span>
+<span id="L126" class="LineNr"> 126 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L62'>&lt;global-keypress&gt;</a></span> [
+<span id="L127" class="LineNr"> 127 </span>  <span class="Comment"># F4? load all code and run all sandboxes.</span>
+<span id="L128" class="LineNr"> 128 </span>  <span class="Delimiter">{</span>
+<span id="L129" class="LineNr"> 129 </span>  <span class="Conceal">¦</span> do-run?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">65532/F4</span>
+<span id="L130" class="LineNr"> 130 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> do-run?
+<span id="L131" class="LineNr"> 131 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L219'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[running...       ]</span>, <span class="Constant">245/grey</span>
+<span id="L132" class="LineNr"> 132 </span>  <span class="Conceal">¦</span> error?:bool <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L149'>run-sandboxes</a> env, <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>
+<span id="L133" class="LineNr"> 133 </span>  <span class="Conceal">¦</span> <span class="Comment"># we could just render-all, but we do some work to minimize the number of prints to screen</span>
+<span id="L134" class="LineNr"> 134 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L134'>&lt;render-recipe-errors-on-F4&gt;</a></span>
+<span id="L135" class="LineNr"> 135 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L136" class="LineNr"> 136 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L137" class="LineNr"> 137 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> error?
+<span id="L138" class="LineNr"> 138 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L219'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[                 ]</span>, <span class="Constant">245/grey</span>
+<span id="L139" class="LineNr"> 139 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L140" class="LineNr"> 140 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L141" class="LineNr"> 141 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> error?
+<span id="L142" class="LineNr"> 142 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L142'>&lt;render-sandbox-errors-on-F4&gt;</a></span>
+<span id="L143" class="LineNr"> 143 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L144" class="LineNr"> 144 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L145" class="LineNr"> 145 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L146" class="LineNr"> 146 </span>  <span class="Delimiter">}</span>
+<span id="L147" class="LineNr"> 147 </span>]
+<span id="L148" class="LineNr"> 148 </span>
+<span id="L149" class="LineNr"> 149 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L149'>run-sandboxes</a> env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a><span class="muRecipe"> -&gt; </span>errors-found?:bool, env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
+<span id="L150" class="LineNr"> 150 </span>  <span class="Constant">local-scope</span>
+<span id="L151" class="LineNr"> 151 </span>  <span class="Constant">load-ingredients</span>
+<span id="L152" class="LineNr"> 152 </span>  errors-found?:bool <span class="Special">&lt;-</span> update-recipes env, <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>
+<span id="L153" class="LineNr"> 153 </span>  <span class="muControl">jump-if</span> errors-found?, <span class="Constant">+return</span>
+<span id="L154" class="LineNr"> 154 </span>  <span class="Comment"># check contents of right editor (sandbox)</span>
+<span id="L155" class="LineNr"> 155 </span><span class="Constant">  <a href='005-sandbox.mu.html#L155'>&lt;run-sandboxes-begin&gt;</a></span>
+<span id="L156" class="LineNr"> 156 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L157" class="LineNr"> 157 </span>  <span class="Delimiter">{</span>
+<span id="L158" class="LineNr"> 158 </span>  <span class="Conceal">¦</span> sandbox-contents:text <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L643'>editor-contents</a> current-sandbox
+<span id="L159" class="LineNr"> 159 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-contents
+<span id="L160" class="LineNr"> 160 </span>  <span class="Conceal">¦</span> <span class="Comment"># if contents exist, first save them</span>
+<span id="L161" class="LineNr"> 161 </span>  <span class="Conceal">¦</span> <span class="Comment"># run them and turn them into a new sandbox</span>
+<span id="L162" class="LineNr"> 162 </span>  <span class="Conceal">¦</span> new-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> new <span class="Constant">sandbox:type</span>
+<span id="L163" class="LineNr"> 163 </span>  <span class="Conceal">¦</span> *new-sandbox <span class="Special">&lt;-</span> put *new-sandbox, <span class="Constant">data:offset</span>, sandbox-contents
+<span id="L164" class="LineNr"> 164 </span>  <span class="Conceal">¦</span> <span class="Comment"># push to head of sandbox list</span>
+<span id="L165" class="LineNr"> 165 </span>  <span class="Conceal">¦</span> dest:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L166" class="LineNr"> 166 </span>  <span class="Conceal">¦</span> *new-sandbox <span class="Special">&lt;-</span> put *new-sandbox, <span class="Constant">next-sandbox:offset</span>, dest
+<span id="L167" class="LineNr"> 167 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox:offset</span>, new-sandbox
+<span id="L168" class="LineNr"> 168 </span>  <span class="Conceal">¦</span> <span class="Comment"># update sandbox count</span>
+<span id="L169" class="LineNr"> 169 </span>  <span class="Conceal">¦</span> sandbox-count:num <span class="Special">&lt;-</span> get *env, <span class="Constant">number-of-sandboxes:offset</span>
+<span id="L170" class="LineNr"> 170 </span>  <span class="Conceal">¦</span> sandbox-count <span class="Special">&lt;-</span> add sandbox-count,<span class="Constant"> 1</span>
+<span id="L171" class="LineNr"> 171 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">number-of-sandboxes:offset</span>, sandbox-count
+<span id="L172" class="LineNr"> 172 </span>  <span class="Conceal">¦</span> <span class="Comment"># clear sandbox editor</span>
+<span id="L173" class="LineNr"> 173 </span>  <span class="Conceal">¦</span> init:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> push <span class="Constant">167/§</span>, <span class="Constant">0/tail</span>
+<span id="L174" class="LineNr"> 174 </span>  <span class="Conceal">¦</span> *current-sandbox <span class="Special">&lt;-</span> put *current-sandbox, <span class="Constant">data:offset</span>, init
+<span id="L175" class="LineNr"> 175 </span>  <span class="Conceal">¦</span> *current-sandbox <span class="Special">&lt;-</span> put *current-sandbox, <span class="Constant">top-of-screen:offset</span>, init
+<span id="L176" class="LineNr"> 176 </span>  <span class="Delimiter">}</span>
+<span id="L177" class="LineNr"> 177 </span>  <span class="Comment"># save all sandboxes before running, just in case we die when running</span>
+<span id="L178" class="LineNr"> 178 </span>  <a href='005-sandbox.mu.html#L226'>save-sandboxes</a> env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L179" class="LineNr"> 179 </span>  <span class="Comment"># run all sandboxes</span>
+<span id="L180" class="LineNr"> 180 </span>  curr:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L181" class="LineNr"> 181 </span>  idx:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
+<span id="L182" class="LineNr"> 182 </span>  <span class="Delimiter">{</span>
+<span id="L183" class="LineNr"> 183 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> curr
+<span id="L184" class="LineNr"> 184 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> update-sandbox curr, env, idx
+<span id="L185" class="LineNr"> 185 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> get *curr, <span class="Constant">next-sandbox:offset</span>
+<span id="L186" class="LineNr"> 186 </span>  <span class="Conceal">¦</span> idx <span class="Special">&lt;-</span> add idx,<span class="Constant"> 1</span>
+<span id="L187" class="LineNr"> 187 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
 <span id="L188" class="LineNr"> 188 </span>  <span class="Delimiter">}</span>
-<span id="L189" class="LineNr"> 189 </span>]
-<span id="L190" class="LineNr"> 190 </span>
-<span id="L191" class="LineNr"> 191 </span><span class="Comment"># load code from disk</span>
-<span id="L192" class="LineNr"> 192 </span><span class="Comment"># replaced in a later layer (whereupon errors-found? will actually be set)</span>
-<span id="L193" class="LineNr"> 193 </span><span class="muRecipe">def</span> update-recipes env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a><span class="muRecipe"> -&gt; </span>errors-found?:bool, env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
-<span id="L194" class="LineNr"> 194 </span>  <span class="Constant">local-scope</span>
-<span id="L195" class="LineNr"> 195 </span>  <span class="Constant">load-ingredients</span>
-<span id="L196" class="LineNr"> 196 </span>  recipes:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">recipes:offset</span>
-<span id="L197" class="LineNr"> 197 </span>  in:text <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L630'>editor-contents</a> recipes
-<span id="L198" class="LineNr"> 198 </span>  <a href='../088file.mu.html#L11'>resources</a> <span class="Special">&lt;-</span> <a href='../088file.mu.html#L127'>dump</a> <a href='../088file.mu.html#L11'>resources</a>, <span class="Constant">[lesson/recipes.mu]</span>, in
-<span id="L199" class="LineNr"> 199 </span>  reload in
-<span id="L200" class="LineNr"> 200 </span>  errors-found? <span class="Special">&lt;-</span> copy <span class="Constant">0/false</span>
-<span id="L201" class="LineNr"> 201 </span>]
-<span id="L202" class="LineNr"> 202 </span>
-<span id="L203" class="LineNr"> 203 </span><span class="Comment"># replaced in a later layer</span>
-<span id="L204" class="LineNr"> 204 </span><span class="muRecipe">def</span> update-sandbox sandbox:&amp;:sandbox, env:&amp;:environment, idx:num<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox, env:&amp;:environment [
-<span id="L205" class="LineNr"> 205 </span>  <span class="Constant">local-scope</span>
-<span id="L206" class="LineNr"> 206 </span>  <span class="Constant">load-ingredients</span>
-<span id="L207" class="LineNr"> 207 </span>  data:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
-<span id="L208" class="LineNr"> 208 </span>  response:text, _, fake-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> run-sandboxed data
-<span id="L209" class="LineNr"> 209 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response:offset</span>, response
-<span id="L210" class="LineNr"> 210 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant"><a href='../081print.mu.html#L4'>screen</a>:offset</span>, fake-screen
-<span id="L211" class="LineNr"> 211 </span>]
-<span id="L212" class="LineNr"> 212 </span>
-<span id="L213" class="LineNr"> 213 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L213'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, msg:text, color:num<span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
-<span id="L214" class="LineNr"> 214 </span>  <span class="Constant">local-scope</span>
-<span id="L215" class="LineNr"> 215 </span>  <span class="Constant">load-ingredients</span>
-<span id="L216" class="LineNr"> 216 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>,<span class="Constant"> 0</span>,<span class="Constant"> 2</span>
-<span id="L217" class="LineNr"> 217 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> print <a href='../081print.mu.html#L4'>screen</a>, msg, color, <span class="Constant">238/grey/background</span>
-<span id="L218" class="LineNr"> 218 </span>]
-<span id="L219" class="LineNr"> 219 </span>
-<span id="L220" class="LineNr"> 220 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L220'>save-sandboxes</a> env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a><span class="muRecipe"> -&gt; </span><a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a> [
-<span id="L221" class="LineNr"> 221 </span>  <span class="Constant">local-scope</span>
-<span id="L222" class="LineNr"> 222 </span>  <span class="Constant">load-ingredients</span>
-<span id="L223" class="LineNr"> 223 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L224" class="LineNr"> 224 </span>  <span class="Comment"># first clear previous versions, in case we deleted some sandbox</span>
-<span id="L225" class="LineNr"> 225 </span>  $system <span class="Constant">[rm lesson/[0-9]</span>* <span class="Constant">&gt;/dev/null</span> 2&gt;/dev/null]  <span class="Comment"># some shells can't handle '&gt;&amp;'</span>
-<span id="L226" class="LineNr"> 226 </span>  curr:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L227" class="LineNr"> 227 </span>  idx:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
-<span id="L228" class="LineNr"> 228 </span>  <span class="Delimiter">{</span>
-<span id="L229" class="LineNr"> 229 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> curr
-<span id="L230" class="LineNr"> 230 </span>  <span class="Conceal">¦</span> data:text <span class="Special">&lt;-</span> get *curr, <span class="Constant">data:offset</span>
-<span id="L231" class="LineNr"> 231 </span>  <span class="Conceal">¦</span> filename:text <span class="Special">&lt;-</span> append <span class="Constant">[lesson/]</span>, idx
-<span id="L232" class="LineNr"> 232 </span>  <span class="Conceal">¦</span> <a href='../088file.mu.html#L11'>resources</a> <span class="Special">&lt;-</span> <a href='../088file.mu.html#L127'>dump</a> <a href='../088file.mu.html#L11'>resources</a>, filename, data
-<span id="L233" class="LineNr"> 233 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L233'>&lt;end-save-sandbox&gt;</a></span>
-<span id="L234" class="LineNr"> 234 </span>  <span class="Conceal">¦</span> idx <span class="Special">&lt;-</span> add idx,<span class="Constant"> 1</span>
-<span id="L235" class="LineNr"> 235 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> get *curr, <span class="Constant">next-sandbox:offset</span>
-<span id="L236" class="LineNr"> 236 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L237" class="LineNr"> 237 </span>  <span class="Delimiter">}</span>
-<span id="L238" class="LineNr"> 238 </span>]
-<span id="L239" class="LineNr"> 239 </span>
-<span id="L240" class="LineNr"> 240 </span><span class="muRecipe">def!</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, env:&amp;:environment, <span class="Delimiter">{</span>render-editor: (recipe (address screen) (address editor)<span class="muRecipe"> -&gt; </span>number number (address screen) (address editor))<span class="Delimiter">}</span><span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, env:&amp;:environment [
-<span id="L241" class="LineNr"> 241 </span>  <span class="Constant">local-scope</span>
-<span id="L242" class="LineNr"> 242 </span>  <span class="Constant">load-ingredients</span>
-<span id="L243" class="LineNr"> 243 </span>  trace<span class="Constant"> 11</span>, <span class="Constant">[app]</span>, <span class="Constant">[render sandbox side]</span>
-<span id="L244" class="LineNr"> 244 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L245" class="LineNr"> 245 </span>  row:num, column:num <span class="Special">&lt;-</span> copy<span class="Constant"> 1</span>,<span class="Constant"> 0</span>
-<span id="L246" class="LineNr"> 246 </span>  left:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
-<span id="L247" class="LineNr"> 247 </span>  right:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">right:offset</span>
-<span id="L248" class="LineNr"> 248 </span>  <span class="Comment"># render sandbox editor</span>
-<span id="L249" class="LineNr"> 249 </span>  render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
-<span id="L250" class="LineNr"> 250 </span>  <span class="Delimiter">{</span>
-<span id="L251" class="LineNr"> 251 </span>  <span class="Conceal">¦</span> render-current-sandbox?:bool <span class="Special">&lt;-</span> equal render-from,<span class="Constant"> -1</span>
-<span id="L252" class="LineNr"> 252 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> render-current-sandbox?
-<span id="L253" class="LineNr"> 253 </span>  <span class="Conceal">¦</span> row, column, <a href='../081print.mu.html#L4'>screen</a>, current-sandbox <span class="Special">&lt;-</span> call render-editor, <a href='../081print.mu.html#L4'>screen</a>, current-sandbox
-<span id="L254" class="LineNr"> 254 </span>  <span class="Conceal">¦</span> <a href='001-editor.mu.html#L207'>clear-screen-from</a> <a href='../081print.mu.html#L4'>screen</a>, row, column, left, right
-<span id="L255" class="LineNr"> 255 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
-<span id="L256" class="LineNr"> 256 </span>  <span class="Delimiter">}</span>
-<span id="L257" class="LineNr"> 257 </span>  <span class="Comment"># render sandboxes</span>
-<span id="L258" class="LineNr"> 258 </span>  <a href='002-typing.mu.html#L1060'>draw-horizontal</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, right
-<span id="L259" class="LineNr"> 259 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L260" class="LineNr"> 260 </span>  row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L264'>render-sandboxes</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox, left, right, row, render-from
-<span id="L261" class="LineNr"> 261 </span>  <a href='001-editor.mu.html#L222'>clear-rest-of-screen</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, right
-<span id="L262" class="LineNr"> 262 </span>]
-<span id="L263" class="LineNr"> 263 </span>
-<span id="L264" class="LineNr"> 264 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L264'>render-sandboxes</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, sandbox:&amp;:sandbox, left:num, right:num, row:num, render-from:num, idx:num<span class="muRecipe"> -&gt; </span>row:num, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, sandbox:&amp;:sandbox [
-<span id="L265" class="LineNr"> 265 </span>  <span class="Constant">local-scope</span>
-<span id="L266" class="LineNr"> 266 </span>  <span class="Constant">load-ingredients</span>
-<span id="L267" class="LineNr"> 267 </span>  <span class="muControl">return-unless</span> sandbox
-<span id="L268" class="LineNr"> 268 </span>  <a href='../081print.mu.html#L748'>screen-height</a>:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> <a href='../081print.mu.html#L4'>screen</a>
-<span id="L269" class="LineNr"> 269 </span>  at-bottom?:bool <span class="Special">&lt;-</span> greater-or-equal row, <a href='../081print.mu.html#L748'>screen-height</a>
-<span id="L270" class="LineNr"> 270 </span>  <span class="muControl">return-if</span> at-bottom?:bool
-<span id="L271" class="LineNr"> 271 </span>  hidden?:bool <span class="Special">&lt;-</span> lesser-than idx, render-from
-<span id="L272" class="LineNr"> 272 </span>  <span class="Delimiter">{</span>
-<span id="L273" class="LineNr"> 273 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> hidden?
-<span id="L274" class="LineNr"> 274 </span>  <span class="Conceal">¦</span> <span class="Comment"># render sandbox menu</span>
-<span id="L275" class="LineNr"> 275 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
-<span id="L276" class="LineNr"> 276 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, left
-<span id="L277" class="LineNr"> 277 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L319'>render-sandbox-menu</a> <a href='../081print.mu.html#L4'>screen</a>, idx, left, right
-<span id="L278" class="LineNr"> 278 </span>  <span class="Conceal">¦</span> <span class="Comment"># save menu row so we can detect clicks to it later</span>
-<span id="L279" class="LineNr"> 279 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">starting-row-on-screen:offset</span>, row
-<span id="L280" class="LineNr"> 280 </span>  <span class="Conceal">¦</span> <span class="Comment"># render sandbox contents</span>
+<span id="L189" class="LineNr"> 189 </span><span class="Constant">  <a href='005-sandbox.mu.html#L189'>&lt;run-sandboxes-end&gt;</a></span>
+<span id="L190" class="LineNr"> 190 </span><span class="Constant">  +return</span>
+<span id="L191" class="LineNr"> 191 </span>  <span class="Delimiter">{</span>
+<span id="L192" class="LineNr"> 192 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> <a href='../088file.mu.html#L11'>resources</a>  <span class="Comment"># ignore this in tests</span>
+<span id="L193" class="LineNr"> 193 </span>  <span class="Conceal">¦</span> $system <span class="Constant">[./snapshot_lesson]</span>
+<span id="L194" class="LineNr"> 194 </span>  <span class="Delimiter">}</span>
+<span id="L195" class="LineNr"> 195 </span>]
+<span id="L196" class="LineNr"> 196 </span>
+<span id="L197" class="LineNr"> 197 </span><span class="Comment"># load code from disk</span>
+<span id="L198" class="LineNr"> 198 </span><span class="Comment"># replaced in a later layer (whereupon errors-found? will actually be set)</span>
+<span id="L199" class="LineNr"> 199 </span><span class="muRecipe">def</span> update-recipes env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a><span class="muRecipe"> -&gt; </span>errors-found?:bool, env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
+<span id="L200" class="LineNr"> 200 </span>  <span class="Constant">local-scope</span>
+<span id="L201" class="LineNr"> 201 </span>  <span class="Constant">load-ingredients</span>
+<span id="L202" class="LineNr"> 202 </span>  recipes:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">recipes:offset</span>
+<span id="L203" class="LineNr"> 203 </span>  in:text <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L643'>editor-contents</a> recipes
+<span id="L204" class="LineNr"> 204 </span>  <a href='../088file.mu.html#L11'>resources</a> <span class="Special">&lt;-</span> <a href='../088file.mu.html#L127'>dump</a> <a href='../088file.mu.html#L11'>resources</a>, <span class="Constant">[lesson/recipes.mu]</span>, in
+<span id="L205" class="LineNr"> 205 </span>  reload in
+<span id="L206" class="LineNr"> 206 </span>  errors-found? <span class="Special">&lt;-</span> copy <span class="Constant">0/false</span>
+<span id="L207" class="LineNr"> 207 </span>]
+<span id="L208" class="LineNr"> 208 </span>
+<span id="L209" class="LineNr"> 209 </span><span class="Comment"># replaced in a later layer</span>
+<span id="L210" class="LineNr"> 210 </span><span class="muRecipe">def</span> update-sandbox sandbox:&amp;:sandbox, env:&amp;:environment, idx:num<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox, env:&amp;:environment [
+<span id="L211" class="LineNr"> 211 </span>  <span class="Constant">local-scope</span>
+<span id="L212" class="LineNr"> 212 </span>  <span class="Constant">load-ingredients</span>
+<span id="L213" class="LineNr"> 213 </span>  data:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
+<span id="L214" class="LineNr"> 214 </span>  response:text, _, fake-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> run-sandboxed data
+<span id="L215" class="LineNr"> 215 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response:offset</span>, response
+<span id="L216" class="LineNr"> 216 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant"><a href='../081print.mu.html#L4'>screen</a>:offset</span>, fake-screen
+<span id="L217" class="LineNr"> 217 </span>]
+<span id="L218" class="LineNr"> 218 </span>
+<span id="L219" class="LineNr"> 219 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L219'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, msg:text, color:num<span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
+<span id="L220" class="LineNr"> 220 </span>  <span class="Constant">local-scope</span>
+<span id="L221" class="LineNr"> 221 </span>  <span class="Constant">load-ingredients</span>
+<span id="L222" class="LineNr"> 222 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>,<span class="Constant"> 0</span>,<span class="Constant"> 2</span>
+<span id="L223" class="LineNr"> 223 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> print <a href='../081print.mu.html#L4'>screen</a>, msg, color, <span class="Constant">238/grey/background</span>
+<span id="L224" class="LineNr"> 224 </span>]
+<span id="L225" class="LineNr"> 225 </span>
+<span id="L226" class="LineNr"> 226 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L226'>save-sandboxes</a> env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a><span class="muRecipe"> -&gt; </span><a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a> [
+<span id="L227" class="LineNr"> 227 </span>  <span class="Constant">local-scope</span>
+<span id="L228" class="LineNr"> 228 </span>  <span class="Constant">load-ingredients</span>
+<span id="L229" class="LineNr"> 229 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L230" class="LineNr"> 230 </span>  <span class="Comment"># first clear previous versions, in case we deleted some sandbox</span>
+<span id="L231" class="LineNr"> 231 </span>  $system <span class="Constant">[rm lesson/[0-9]</span>* <span class="Constant">&gt;/dev/null</span> 2&gt;/dev/null]  <span class="Comment"># some shells can't handle '&gt;&amp;'</span>
+<span id="L232" class="LineNr"> 232 </span>  curr:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L233" class="LineNr"> 233 </span>  idx:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
+<span id="L234" class="LineNr"> 234 </span>  <span class="Delimiter">{</span>
+<span id="L235" class="LineNr"> 235 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> curr
+<span id="L236" class="LineNr"> 236 </span>  <span class="Conceal">¦</span> data:text <span class="Special">&lt;-</span> get *curr, <span class="Constant">data:offset</span>
+<span id="L237" class="LineNr"> 237 </span>  <span class="Conceal">¦</span> filename:text <span class="Special">&lt;-</span> append <span class="Constant">[lesson/]</span>, idx
+<span id="L238" class="LineNr"> 238 </span>  <span class="Conceal">¦</span> <a href='../088file.mu.html#L11'>resources</a> <span class="Special">&lt;-</span> <a href='../088file.mu.html#L127'>dump</a> <a href='../088file.mu.html#L11'>resources</a>, filename, data
+<span id="L239" class="LineNr"> 239 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L239'>&lt;end-save-sandbox&gt;</a></span>
+<span id="L240" class="LineNr"> 240 </span>  <span class="Conceal">¦</span> idx <span class="Special">&lt;-</span> add idx,<span class="Constant"> 1</span>
+<span id="L241" class="LineNr"> 241 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> get *curr, <span class="Constant">next-sandbox:offset</span>
+<span id="L242" class="LineNr"> 242 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L243" class="LineNr"> 243 </span>  <span class="Delimiter">}</span>
+<span id="L244" class="LineNr"> 244 </span>]
+<span id="L245" class="LineNr"> 245 </span>
+<span id="L246" class="LineNr"> 246 </span><span class="muRecipe">def!</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, env:&amp;:environment, <span class="Delimiter">{</span>render-editor: (recipe (address screen) (address editor)<span class="muRecipe"> -&gt; </span>number number (address screen) (address editor))<span class="Delimiter">}</span><span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, env:&amp;:environment [
+<span id="L247" class="LineNr"> 247 </span>  <span class="Constant">local-scope</span>
+<span id="L248" class="LineNr"> 248 </span>  <span class="Constant">load-ingredients</span>
+<span id="L249" class="LineNr"> 249 </span>  trace<span class="Constant"> 11</span>, <span class="Constant">[app]</span>, <span class="Constant">[render sandbox side]</span>
+<span id="L250" class="LineNr"> 250 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L251" class="LineNr"> 251 </span>  row:num, column:num <span class="Special">&lt;-</span> copy<span class="Constant"> 1</span>,<span class="Constant"> 0</span>
+<span id="L252" class="LineNr"> 252 </span>  left:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
+<span id="L253" class="LineNr"> 253 </span>  right:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">right:offset</span>
+<span id="L254" class="LineNr"> 254 </span>  <span class="Comment"># render sandbox editor</span>
+<span id="L255" class="LineNr"> 255 </span>  render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
+<span id="L256" class="LineNr"> 256 </span>  <span class="Delimiter">{</span>
+<span id="L257" class="LineNr"> 257 </span>  <span class="Conceal">¦</span> render-current-sandbox?:bool <span class="Special">&lt;-</span> equal render-from,<span class="Constant"> -1</span>
+<span id="L258" class="LineNr"> 258 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> render-current-sandbox?
+<span id="L259" class="LineNr"> 259 </span>  <span class="Conceal">¦</span> row, column, <a href='../081print.mu.html#L4'>screen</a>, current-sandbox <span class="Special">&lt;-</span> call render-editor, <a href='../081print.mu.html#L4'>screen</a>, current-sandbox
+<span id="L260" class="LineNr"> 260 </span>  <span class="Conceal">¦</span> <a href='001-editor.mu.html#L207'>clear-screen-from</a> <a href='../081print.mu.html#L4'>screen</a>, row, column, left, right
+<span id="L261" class="LineNr"> 261 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L262" class="LineNr"> 262 </span>  <span class="Delimiter">}</span>
+<span id="L263" class="LineNr"> 263 </span>  <span class="Comment"># render sandboxes</span>
+<span id="L264" class="LineNr"> 264 </span>  <a href='002-typing.mu.html#L1060'>draw-horizontal</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, right
+<span id="L265" class="LineNr"> 265 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L266" class="LineNr"> 266 </span>  row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L270'>render-sandboxes</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox, left, right, row, render-from
+<span id="L267" class="LineNr"> 267 </span>  <a href='001-editor.mu.html#L222'>clear-rest-of-screen</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, right
+<span id="L268" class="LineNr"> 268 </span>]
+<span id="L269" class="LineNr"> 269 </span>
+<span id="L270" class="LineNr"> 270 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L270'>render-sandboxes</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, sandbox:&amp;:sandbox, left:num, right:num, row:num, render-from:num, idx:num<span class="muRecipe"> -&gt; </span>row:num, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, sandbox:&amp;:sandbox [
+<span id="L271" class="LineNr"> 271 </span>  <span class="Constant">local-scope</span>
+<span id="L272" class="LineNr"> 272 </span>  <span class="Constant">load-ingredients</span>
+<span id="L273" class="LineNr"> 273 </span>  <span class="muControl">return-unless</span> sandbox
+<span id="L274" class="LineNr"> 274 </span>  <a href='../081print.mu.html#L748'>screen-height</a>:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> <a href='../081print.mu.html#L4'>screen</a>
+<span id="L275" class="LineNr"> 275 </span>  at-bottom?:bool <span class="Special">&lt;-</span> greater-or-equal row, <a href='../081print.mu.html#L748'>screen-height</a>
+<span id="L276" class="LineNr"> 276 </span>  <span class="muControl">return-if</span> at-bottom?:bool
+<span id="L277" class="LineNr"> 277 </span>  hidden?:bool <span class="Special">&lt;-</span> lesser-than idx, render-from
+<span id="L278" class="LineNr"> 278 </span>  <span class="Delimiter">{</span>
+<span id="L279" class="LineNr"> 279 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> hidden?
+<span id="L280" class="LineNr"> 280 </span>  <span class="Conceal">¦</span> <span class="Comment"># render sandbox menu</span>
 <span id="L281" class="LineNr"> 281 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
 <span id="L282" class="LineNr"> 282 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, left
-<span id="L283" class="LineNr"> 283 </span>  <span class="Conceal">¦</span> sandbox-data:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
-<span id="L284" class="LineNr"> 284 </span>  <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='003-shortcuts.mu.html#L1719'>render-code</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-data, left, right, row
-<span id="L285" class="LineNr"> 285 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">code-ending-row-on-screen:offset</span>, row
-<span id="L286" class="LineNr"> 286 </span>  <span class="Conceal">¦</span> <span class="Comment"># render sandbox warnings, screen or response, in that order</span>
-<span id="L287" class="LineNr"> 287 </span>  <span class="Conceal">¦</span> sandbox-response:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">response:offset</span>
-<span id="L288" class="LineNr"> 288 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L288'>&lt;render-sandbox-results&gt;</a></span>
-<span id="L289" class="LineNr"> 289 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L290" class="LineNr"> 290 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> sandbox-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> get *sandbox, <span class="Constant"><a href='../081print.mu.html#L4'>screen</a>:offset</span>
-<span id="L291" class="LineNr"> 291 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> empty-screen?:bool <span class="Special">&lt;-</span> <a href='../081print.mu.html#L60'>fake-screen-is-empty?</a> sandbox-screen
-<span id="L292" class="LineNr"> 292 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> empty-screen?
-<span id="L293" class="LineNr"> 293 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L472'>render-screen</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-screen, left, right, row
-<span id="L294" class="LineNr"> 294 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L283" class="LineNr"> 283 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L325'>render-sandbox-menu</a> <a href='../081print.mu.html#L4'>screen</a>, idx, left, right
+<span id="L284" class="LineNr"> 284 </span>  <span class="Conceal">¦</span> <span class="Comment"># save menu row so we can detect clicks to it later</span>
+<span id="L285" class="LineNr"> 285 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">starting-row-on-screen:offset</span>, row
+<span id="L286" class="LineNr"> 286 </span>  <span class="Conceal">¦</span> <span class="Comment"># render sandbox contents</span>
+<span id="L287" class="LineNr"> 287 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L288" class="LineNr"> 288 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, left
+<span id="L289" class="LineNr"> 289 </span>  <span class="Conceal">¦</span> sandbox-data:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
+<span id="L290" class="LineNr"> 290 </span>  <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='003-shortcuts.mu.html#L1719'>render-code</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-data, left, right, row
+<span id="L291" class="LineNr"> 291 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">code-ending-row-on-screen:offset</span>, row
+<span id="L292" class="LineNr"> 292 </span>  <span class="Conceal">¦</span> <span class="Comment"># render sandbox warnings, screen or response, in that order</span>
+<span id="L293" class="LineNr"> 293 </span>  <span class="Conceal">¦</span> sandbox-response:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">response:offset</span>
+<span id="L294" class="LineNr"> 294 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L294'>&lt;render-sandbox-results&gt;</a></span>
 <span id="L295" class="LineNr"> 295 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L296" class="LineNr"> 296 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> empty-screen?
-<span id="L297" class="LineNr"> 297 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L297'>&lt;render-sandbox-response&gt;</a></span>
-<span id="L298" class="LineNr"> 298 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L360'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-response, left, right, <span class="Constant">245/grey</span>, row
-<span id="L299" class="LineNr"> 299 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L300" class="LineNr"> 300 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> +render-sandbox-end</span>
-<span id="L301" class="LineNr"> 301 </span>  <span class="Conceal">¦</span> at-bottom?:bool <span class="Special">&lt;-</span> greater-or-equal row, <a href='../081print.mu.html#L748'>screen-height</a>
-<span id="L302" class="LineNr"> 302 </span>  <span class="Conceal">¦</span> <span class="muControl">return-if</span> at-bottom?
-<span id="L303" class="LineNr"> 303 </span>  <span class="Conceal">¦</span> <span class="Comment"># draw solid line after sandbox</span>
-<span id="L304" class="LineNr"> 304 </span>  <span class="Conceal">¦</span> <a href='002-typing.mu.html#L1060'>draw-horizontal</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, right
-<span id="L305" class="LineNr"> 305 </span>  <span class="Delimiter">}</span>
-<span id="L306" class="LineNr"> 306 </span>  <span class="Comment"># if hidden, reset row attributes</span>
-<span id="L307" class="LineNr"> 307 </span>  <span class="Delimiter">{</span>
-<span id="L308" class="LineNr"> 308 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> hidden?
-<span id="L309" class="LineNr"> 309 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">starting-row-on-screen:offset</span>,<span class="Constant"> 0</span>
-<span id="L310" class="LineNr"> 310 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">code-ending-row-on-screen:offset</span>,<span class="Constant"> 0</span>
-<span id="L311" class="LineNr"> 311 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L311'>&lt;end-render-sandbox-reset-hidden&gt;</a></span>
-<span id="L312" class="LineNr"> 312 </span>  <span class="Delimiter">}</span>
-<span id="L313" class="LineNr"> 313 </span>  <span class="Comment"># draw next sandbox</span>
-<span id="L314" class="LineNr"> 314 </span>  next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">next-sandbox:offset</span>
-<span id="L315" class="LineNr"> 315 </span>  next-idx:num <span class="Special">&lt;-</span> add idx,<span class="Constant"> 1</span>
-<span id="L316" class="LineNr"> 316 </span>  row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L264'>render-sandboxes</a> <a href='../081print.mu.html#L4'>screen</a>, next-sandbox, left, right, row, render-from, next-idx
-<span id="L317" class="LineNr"> 317 </span>]
-<span id="L318" class="LineNr"> 318 </span>
-<span id="L319" class="LineNr"> 319 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L319'>render-sandbox-menu</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, sandbox-index:num, left:num, right:num<span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
-<span id="L320" class="LineNr"> 320 </span>  <span class="Constant">local-scope</span>
-<span id="L321" class="LineNr"> 321 </span>  <span class="Constant">load-ingredients</span>
-<span id="L322" class="LineNr"> 322 </span>  <a href='../081print.mu.html#L728'>move-cursor-to-column</a> <a href='../081print.mu.html#L4'>screen</a>, left
-<span id="L323" class="LineNr"> 323 </span>  edit-button-left:num, edit-button-right:num, copy-button-left:num, copy-button-right:num, recipe-button-left:num, recipe-button-right:num, delete-button-left:num <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L340'>sandbox-menu-columns</a> left, right
-<span id="L324" class="LineNr"> 324 </span>  print <a href='../081print.mu.html#L4'>screen</a>, sandbox-index, <span class="Constant">232/dark-grey</span>, <span class="Constant">245/grey</span>
-<span id="L325" class="LineNr"> 325 </span>  start-buttons:num <span class="Special">&lt;-</span> subtract edit-button-left,<span class="Constant"> 1</span>
-<span id="L326" class="LineNr"> 326 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, start-buttons, <span class="Constant">245/grey</span>
-<span id="L327" class="LineNr"> 327 </span>  print <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[edit]</span>, <span class="Constant">232/black</span>, <span class="Constant">25/background-blue</span>
-<span id="L328" class="LineNr"> 328 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, edit-button-right, <span class="Constant">25/background-blue</span>
-<span id="L329" class="LineNr"> 329 </span>  print <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[copy]</span>, <span class="Constant">232/black</span>, <span class="Constant">58/background-green</span>
-<span id="L330" class="LineNr"> 330 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, copy-button-right, <span class="Constant">58/background-green</span>
-<span id="L331" class="LineNr"> 331 </span>  print <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[to recipe]</span>, <span class="Constant">232/black</span>, <span class="Constant">94/background-orange</span>
-<span id="L332" class="LineNr"> 332 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, recipe-button-right, <span class="Constant">94/background-orange</span>
-<span id="L333" class="LineNr"> 333 </span>  print <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[delete]</span>, <span class="Constant">232/black</span>, <span class="Constant">52/background-red</span>
-<span id="L334" class="LineNr"> 334 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, right, <span class="Constant">52/background-red</span>
-<span id="L335" class="LineNr"> 335 </span>]
-<span id="L336" class="LineNr"> 336 </span>
-<span id="L337" class="LineNr"> 337 </span><span class="Comment"># divide up the menu bar for a sandbox into 3 segments, for edit/copy/delete buttons</span>
-<span id="L338" class="LineNr"> 338 </span><span class="Comment"># delete-button-right == right</span>
-<span id="L339" class="LineNr"> 339 </span><span class="Comment"># all left/right pairs are inclusive</span>
-<span id="L340" class="LineNr"> 340 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L340'>sandbox-menu-columns</a> left:num, right:num<span class="muRecipe"> -&gt; </span>edit-button-left:num, edit-button-right:num, copy-button-left:num, copy-button-right:num, recipe-button-left:num, recipe-button-right:num, delete-button-left:num [
-<span id="L341" class="LineNr"> 341 </span>  <span class="Constant">local-scope</span>
-<span id="L342" class="LineNr"> 342 </span>  <span class="Constant">load-ingredients</span>
-<span id="L343" class="LineNr"> 343 </span>  start-buttons:num <span class="Special">&lt;-</span> add left, <span class="Constant">4/space-for-sandbox-index</span>
-<span id="L344" class="LineNr"> 344 </span>  buttons-space:num <span class="Special">&lt;-</span> subtract right, start-buttons
-<span id="L345" class="LineNr"> 345 </span>  button-width:num <span class="Special">&lt;-</span> divide-with-remainder buttons-space,<span class="Constant"> 4</span>  <span class="Comment"># integer division</span>
-<span id="L346" class="LineNr"> 346 </span>  buttons-wide-enough?:bool <span class="Special">&lt;-</span> greater-or-equal button-width,<span class="Constant"> 10</span>
-<span id="L347" class="LineNr"> 347 </span>  assert buttons-wide-enough?, <span class="Constant">[sandbox must be at least 40 or so characters wide]</span>
-<span id="L348" class="LineNr"> 348 </span>  edit-button-left:num <span class="Special">&lt;-</span> copy start-buttons
-<span id="L349" class="LineNr"> 349 </span>  copy-button-left:num <span class="Special">&lt;-</span> add start-buttons, button-width
-<span id="L350" class="LineNr"> 350 </span>  edit-button-right:num <span class="Special">&lt;-</span> subtract copy-button-left,<span class="Constant"> 1</span>
-<span id="L351" class="LineNr"> 351 </span>  recipe-button-left:num <span class="Special">&lt;-</span> add copy-button-left, button-width
-<span id="L352" class="LineNr"> 352 </span>  copy-button-right:num <span class="Special">&lt;-</span> subtract recipe-button-left,<span class="Constant"> 1</span>
-<span id="L353" class="LineNr"> 353 </span>  delete-button-left:num <span class="Special">&lt;-</span> subtract right, button-width,<span class="Constant"> -2</span>  <span class="Comment"># because 'to recipe' is wider than 'delete'</span>
-<span id="L354" class="LineNr"> 354 </span>  recipe-button-right:num <span class="Special">&lt;-</span> subtract delete-button-left,<span class="Constant"> 1</span>
-<span id="L355" class="LineNr"> 355 </span>]
-<span id="L356" class="LineNr"> 356 </span>
-<span id="L357" class="LineNr"> 357 </span><span class="Comment"># print a text 's' to 'editor' in 'color' starting at 'row'</span>
-<span id="L358" class="LineNr"> 358 </span><span class="Comment"># clear rest of last line, move cursor to next line</span>
-<span id="L359" class="LineNr"> 359 </span><span class="Comment"># like 'render-code' but without syntax-based colorization</span>
-<span id="L360" class="LineNr"> 360 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L360'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, s:text, left:num, right:num, color:num, row:num<span class="muRecipe"> -&gt; </span>row:num, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
-<span id="L361" class="LineNr"> 361 </span>  <span class="Constant">local-scope</span>
-<span id="L362" class="LineNr"> 362 </span>  <span class="Constant">load-ingredients</span>
-<span id="L363" class="LineNr"> 363 </span>  <span class="muControl">return-unless</span> s
-<span id="L364" class="LineNr"> 364 </span>  column:num <span class="Special">&lt;-</span> copy left
-<span id="L365" class="LineNr"> 365 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, column
-<span id="L366" class="LineNr"> 366 </span>  <a href='../081print.mu.html#L748'>screen-height</a>:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> <a href='../081print.mu.html#L4'>screen</a>
-<span id="L367" class="LineNr"> 367 </span>  i:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
-<span id="L368" class="LineNr"> 368 </span>  len:num <span class="Special">&lt;-</span> length *s
-<span id="L369" class="LineNr"> 369 </span>  <span class="Delimiter">{</span>
-<span id="L370" class="LineNr"> 370 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> +next-character</span>
-<span id="L371" class="LineNr"> 371 </span>  <span class="Conceal">¦</span> done?:bool <span class="Special">&lt;-</span> greater-or-equal i, len
-<span id="L372" class="LineNr"> 372 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
-<span id="L373" class="LineNr"> 373 </span>  <span class="Conceal">¦</span> done? <span class="Special">&lt;-</span> greater-or-equal row, <a href='../081print.mu.html#L748'>screen-height</a>
-<span id="L374" class="LineNr"> 374 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
-<span id="L375" class="LineNr"> 375 </span>  <span class="Conceal">¦</span> c:char <span class="Special">&lt;-</span> index *s, i
-<span id="L376" class="LineNr"> 376 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L377" class="LineNr"> 377 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># newline? move to left rather than 0</span>
-<span id="L378" class="LineNr"> 378 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> newline?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">10/newline</span>
-<span id="L379" class="LineNr"> 379 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> newline?
-<span id="L380" class="LineNr"> 380 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># clear rest of line in this window</span>
-<span id="L381" class="LineNr"> 381 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L382" class="LineNr"> 382 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> done?:bool <span class="Special">&lt;-</span> greater-than column, right
-<span id="L383" class="LineNr"> 383 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
-<span id="L384" class="LineNr"> 384 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> space:char <span class="Special">&lt;-</span> copy <span class="Constant">32/space</span>
-<span id="L385" class="LineNr"> 385 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, space
-<span id="L386" class="LineNr"> 386 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
-<span id="L387" class="LineNr"> 387 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L388" class="LineNr"> 388 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L389" class="LineNr"> 389 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
-<span id="L390" class="LineNr"> 390 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> copy left
-<span id="L391" class="LineNr"> 391 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, column
-<span id="L392" class="LineNr"> 392 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> i <span class="Special">&lt;-</span> add i,<span class="Constant"> 1</span>
-<span id="L393" class="LineNr"> 393 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-character</span>
-<span id="L394" class="LineNr"> 394 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L395" class="LineNr"> 395 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L396" class="LineNr"> 396 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># at right? wrap.</span>
-<span id="L397" class="LineNr"> 397 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> at-right?:bool <span class="Special">&lt;-</span> equal column, right
-<span id="L398" class="LineNr"> 398 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> at-right?
-<span id="L399" class="LineNr"> 399 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># print wrap icon</span>
-<span id="L400" class="LineNr"> 400 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> wrap-icon:char <span class="Special">&lt;-</span> copy <span class="Constant">8617/loop-back-to-left</span>
-<span id="L401" class="LineNr"> 401 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, wrap-icon, <span class="Constant">245/grey</span>
-<span id="L402" class="LineNr"> 402 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> copy left
-<span id="L403" class="LineNr"> 403 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
-<span id="L404" class="LineNr"> 404 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, column
-<span id="L405" class="LineNr"> 405 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># don't increment i</span>
-<span id="L406" class="LineNr"> 406 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-character</span>
-<span id="L407" class="LineNr"> 407 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L408" class="LineNr"> 408 </span>  <span class="Conceal">¦</span> i <span class="Special">&lt;-</span> add i,<span class="Constant"> 1</span>
-<span id="L409" class="LineNr"> 409 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, c, color
-<span id="L410" class="LineNr"> 410 </span>  <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
-<span id="L411" class="LineNr"> 411 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L412" class="LineNr"> 412 </span>  <span class="Delimiter">}</span>
-<span id="L413" class="LineNr"> 413 </span>  was-at-left?:bool <span class="Special">&lt;-</span> equal column, left
-<span id="L414" class="LineNr"> 414 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, right
-<span id="L415" class="LineNr"> 415 </span>  <span class="Delimiter">{</span>
-<span id="L416" class="LineNr"> 416 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> was-at-left?
-<span id="L417" class="LineNr"> 417 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L296" class="LineNr"> 296 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> sandbox-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> get *sandbox, <span class="Constant"><a href='../081print.mu.html#L4'>screen</a>:offset</span>
+<span id="L297" class="LineNr"> 297 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> empty-screen?:bool <span class="Special">&lt;-</span> <a href='../081print.mu.html#L60'>fake-screen-is-empty?</a> sandbox-screen
+<span id="L298" class="LineNr"> 298 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> empty-screen?
+<span id="L299" class="LineNr"> 299 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L478'>render-screen</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-screen, left, right, row
+<span id="L300" class="LineNr"> 300 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L301" class="LineNr"> 301 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L302" class="LineNr"> 302 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> empty-screen?
+<span id="L303" class="LineNr"> 303 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L303'>&lt;render-sandbox-response&gt;</a></span>
+<span id="L304" class="LineNr"> 304 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L366'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-response, left, right, <span class="Constant">245/grey</span>, row
+<span id="L305" class="LineNr"> 305 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L306" class="LineNr"> 306 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> +render-sandbox-end</span>
+<span id="L307" class="LineNr"> 307 </span>  <span class="Conceal">¦</span> at-bottom?:bool <span class="Special">&lt;-</span> greater-or-equal row, <a href='../081print.mu.html#L748'>screen-height</a>
+<span id="L308" class="LineNr"> 308 </span>  <span class="Conceal">¦</span> <span class="muControl">return-if</span> at-bottom?
+<span id="L309" class="LineNr"> 309 </span>  <span class="Conceal">¦</span> <span class="Comment"># draw solid line after sandbox</span>
+<span id="L310" class="LineNr"> 310 </span>  <span class="Conceal">¦</span> <a href='002-typing.mu.html#L1060'>draw-horizontal</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, right
+<span id="L311" class="LineNr"> 311 </span>  <span class="Delimiter">}</span>
+<span id="L312" class="LineNr"> 312 </span>  <span class="Comment"># if hidden, reset row attributes</span>
+<span id="L313" class="LineNr"> 313 </span>  <span class="Delimiter">{</span>
+<span id="L314" class="LineNr"> 314 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> hidden?
+<span id="L315" class="LineNr"> 315 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">starting-row-on-screen:offset</span>,<span class="Constant"> 0</span>
+<span id="L316" class="LineNr"> 316 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">code-ending-row-on-screen:offset</span>,<span class="Constant"> 0</span>
+<span id="L317" class="LineNr"> 317 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L317'>&lt;end-render-sandbox-reset-hidden&gt;</a></span>
+<span id="L318" class="LineNr"> 318 </span>  <span class="Delimiter">}</span>
+<span id="L319" class="LineNr"> 319 </span>  <span class="Comment"># draw next sandbox</span>
+<span id="L320" class="LineNr"> 320 </span>  next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">next-sandbox:offset</span>
+<span id="L321" class="LineNr"> 321 </span>  next-idx:num <span class="Special">&lt;-</span> add idx,<span class="Constant"> 1</span>
+<span id="L322" class="LineNr"> 322 </span>  row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L270'>render-sandboxes</a> <a href='../081print.mu.html#L4'>screen</a>, next-sandbox, left, right, row, render-from, next-idx
+<span id="L323" class="LineNr"> 323 </span>]
+<span id="L324" class="LineNr"> 324 </span>
+<span id="L325" class="LineNr"> 325 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L325'>render-sandbox-menu</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, sandbox-index:num, left:num, right:num<span class="muRecipe"> -&gt; </span><a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
+<span id="L326" class="LineNr"> 326 </span>  <span class="Constant">local-scope</span>
+<span id="L327" class="LineNr"> 327 </span>  <span class="Constant">load-ingredients</span>
+<span id="L328" class="LineNr"> 328 </span>  <a href='../081print.mu.html#L728'>move-cursor-to-column</a> <a href='../081print.mu.html#L4'>screen</a>, left
+<span id="L329" class="LineNr"> 329 </span>  edit-button-left:num, edit-button-right:num, copy-button-left:num, copy-button-right:num, recipe-button-left:num, recipe-button-right:num, delete-button-left:num <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L346'>sandbox-menu-columns</a> left, right
+<span id="L330" class="LineNr"> 330 </span>  print <a href='../081print.mu.html#L4'>screen</a>, sandbox-index, <span class="Constant">232/dark-grey</span>, <span class="Constant">245/grey</span>
+<span id="L331" class="LineNr"> 331 </span>  start-buttons:num <span class="Special">&lt;-</span> subtract edit-button-left,<span class="Constant"> 1</span>
+<span id="L332" class="LineNr"> 332 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, start-buttons, <span class="Constant">245/grey</span>
+<span id="L333" class="LineNr"> 333 </span>  print <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[edit]</span>, <span class="Constant">232/black</span>, <span class="Constant">25/background-blue</span>
+<span id="L334" class="LineNr"> 334 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, edit-button-right, <span class="Constant">25/background-blue</span>
+<span id="L335" class="LineNr"> 335 </span>  print <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[copy]</span>, <span class="Constant">232/black</span>, <span class="Constant">58/background-green</span>
+<span id="L336" class="LineNr"> 336 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, copy-button-right, <span class="Constant">58/background-green</span>
+<span id="L337" class="LineNr"> 337 </span>  print <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[to recipe]</span>, <span class="Constant">232/black</span>, <span class="Constant">94/background-orange</span>
+<span id="L338" class="LineNr"> 338 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, recipe-button-right, <span class="Constant">94/background-orange</span>
+<span id="L339" class="LineNr"> 339 </span>  print <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[delete]</span>, <span class="Constant">232/black</span>, <span class="Constant">52/background-red</span>
+<span id="L340" class="LineNr"> 340 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, right, <span class="Constant">52/background-red</span>
+<span id="L341" class="LineNr"> 341 </span>]
+<span id="L342" class="LineNr"> 342 </span>
+<span id="L343" class="LineNr"> 343 </span><span class="Comment"># divide up the menu bar for a sandbox into 3 segments, for edit/copy/delete buttons</span>
+<span id="L344" class="LineNr"> 344 </span><span class="Comment"># delete-button-right == right</span>
+<span id="L345" class="LineNr"> 345 </span><span class="Comment"># all left/right pairs are inclusive</span>
+<span id="L346" class="LineNr"> 346 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L346'>sandbox-menu-columns</a> left:num, right:num<span class="muRecipe"> -&gt; </span>edit-button-left:num, edit-button-right:num, copy-button-left:num, copy-button-right:num, recipe-button-left:num, recipe-button-right:num, delete-button-left:num [
+<span id="L347" class="LineNr"> 347 </span>  <span class="Constant">local-scope</span>
+<span id="L348" class="LineNr"> 348 </span>  <span class="Constant">load-ingredients</span>
+<span id="L349" class="LineNr"> 349 </span>  start-buttons:num <span class="Special">&lt;-</span> add left, <span class="Constant">4/space-for-sandbox-index</span>
+<span id="L350" class="LineNr"> 350 </span>  buttons-space:num <span class="Special">&lt;-</span> subtract right, start-buttons
+<span id="L351" class="LineNr"> 351 </span>  button-width:num <span class="Special">&lt;-</span> divide-with-remainder buttons-space,<span class="Constant"> 4</span>  <span class="Comment"># integer division</span>
+<span id="L352" class="LineNr"> 352 </span>  buttons-wide-enough?:bool <span class="Special">&lt;-</span> greater-or-equal button-width,<span class="Constant"> 10</span>
+<span id="L353" class="LineNr"> 353 </span>  assert buttons-wide-enough?, <span class="Constant">[sandbox must be at least 40 or so characters wide]</span>
+<span id="L354" class="LineNr"> 354 </span>  edit-button-left:num <span class="Special">&lt;-</span> copy start-buttons
+<span id="L355" class="LineNr"> 355 </span>  copy-button-left:num <span class="Special">&lt;-</span> add start-buttons, button-width
+<span id="L356" class="LineNr"> 356 </span>  edit-button-right:num <span class="Special">&lt;-</span> subtract copy-button-left,<span class="Constant"> 1</span>
+<span id="L357" class="LineNr"> 357 </span>  recipe-button-left:num <span class="Special">&lt;-</span> add copy-button-left, button-width
+<span id="L358" class="LineNr"> 358 </span>  copy-button-right:num <span class="Special">&lt;-</span> subtract recipe-button-left,<span class="Constant"> 1</span>
+<span id="L359" class="LineNr"> 359 </span>  delete-button-left:num <span class="Special">&lt;-</span> subtract right, button-width,<span class="Constant"> -2</span>  <span class="Comment"># because 'to recipe' is wider than 'delete'</span>
+<span id="L360" class="LineNr"> 360 </span>  recipe-button-right:num <span class="Special">&lt;-</span> subtract delete-button-left,<span class="Constant"> 1</span>
+<span id="L361" class="LineNr"> 361 </span>]
+<span id="L362" class="LineNr"> 362 </span>
+<span id="L363" class="LineNr"> 363 </span><span class="Comment"># print a text 's' to 'editor' in 'color' starting at 'row'</span>
+<span id="L364" class="LineNr"> 364 </span><span class="Comment"># clear rest of last line, move cursor to next line</span>
+<span id="L365" class="LineNr"> 365 </span><span class="Comment"># like 'render-code' but without syntax-based colorization</span>
+<span id="L366" class="LineNr"> 366 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L366'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, s:text, left:num, right:num, color:num, row:num<span class="muRecipe"> -&gt; </span>row:num, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
+<span id="L367" class="LineNr"> 367 </span>  <span class="Constant">local-scope</span>
+<span id="L368" class="LineNr"> 368 </span>  <span class="Constant">load-ingredients</span>
+<span id="L369" class="LineNr"> 369 </span>  <span class="muControl">return-unless</span> s
+<span id="L370" class="LineNr"> 370 </span>  column:num <span class="Special">&lt;-</span> copy left
+<span id="L371" class="LineNr"> 371 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, column
+<span id="L372" class="LineNr"> 372 </span>  <a href='../081print.mu.html#L748'>screen-height</a>:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> <a href='../081print.mu.html#L4'>screen</a>
+<span id="L373" class="LineNr"> 373 </span>  i:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
+<span id="L374" class="LineNr"> 374 </span>  len:num <span class="Special">&lt;-</span> length *s
+<span id="L375" class="LineNr"> 375 </span>  <span class="Delimiter">{</span>
+<span id="L376" class="LineNr"> 376 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> +next-character</span>
+<span id="L377" class="LineNr"> 377 </span>  <span class="Conceal">¦</span> done?:bool <span class="Special">&lt;-</span> greater-or-equal i, len
+<span id="L378" class="LineNr"> 378 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
+<span id="L379" class="LineNr"> 379 </span>  <span class="Conceal">¦</span> done? <span class="Special">&lt;-</span> greater-or-equal row, <a href='../081print.mu.html#L748'>screen-height</a>
+<span id="L380" class="LineNr"> 380 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
+<span id="L381" class="LineNr"> 381 </span>  <span class="Conceal">¦</span> c:char <span class="Special">&lt;-</span> index *s, i
+<span id="L382" class="LineNr"> 382 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L383" class="LineNr"> 383 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># newline? move to left rather than 0</span>
+<span id="L384" class="LineNr"> 384 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> newline?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">10/newline</span>
+<span id="L385" class="LineNr"> 385 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> newline?
+<span id="L386" class="LineNr"> 386 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># clear rest of line in this window</span>
+<span id="L387" class="LineNr"> 387 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L388" class="LineNr"> 388 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> done?:bool <span class="Special">&lt;-</span> greater-than column, right
+<span id="L389" class="LineNr"> 389 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
+<span id="L390" class="LineNr"> 390 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> space:char <span class="Special">&lt;-</span> copy <span class="Constant">32/space</span>
+<span id="L391" class="LineNr"> 391 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, space
+<span id="L392" class="LineNr"> 392 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
+<span id="L393" class="LineNr"> 393 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L394" class="LineNr"> 394 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L395" class="LineNr"> 395 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L396" class="LineNr"> 396 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> copy left
+<span id="L397" class="LineNr"> 397 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, column
+<span id="L398" class="LineNr"> 398 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> i <span class="Special">&lt;-</span> add i,<span class="Constant"> 1</span>
+<span id="L399" class="LineNr"> 399 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-character</span>
+<span id="L400" class="LineNr"> 400 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L401" class="LineNr"> 401 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L402" class="LineNr"> 402 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># at right? wrap.</span>
+<span id="L403" class="LineNr"> 403 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> at-right?:bool <span class="Special">&lt;-</span> equal column, right
+<span id="L404" class="LineNr"> 404 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> at-right?
+<span id="L405" class="LineNr"> 405 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># print wrap icon</span>
+<span id="L406" class="LineNr"> 406 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> wrap-icon:char <span class="Special">&lt;-</span> copy <span class="Constant">8617/loop-back-to-left</span>
+<span id="L407" class="LineNr"> 407 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, wrap-icon, <span class="Constant">245/grey</span>
+<span id="L408" class="LineNr"> 408 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> copy left
+<span id="L409" class="LineNr"> 409 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L410" class="LineNr"> 410 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, column
+<span id="L411" class="LineNr"> 411 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># don't increment i</span>
+<span id="L412" class="LineNr"> 412 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-character</span>
+<span id="L413" class="LineNr"> 413 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L414" class="LineNr"> 414 </span>  <span class="Conceal">¦</span> i <span class="Special">&lt;-</span> add i,<span class="Constant"> 1</span>
+<span id="L415" class="LineNr"> 415 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, c, color
+<span id="L416" class="LineNr"> 416 </span>  <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
+<span id="L417" class="LineNr"> 417 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
 <span id="L418" class="LineNr"> 418 </span>  <span class="Delimiter">}</span>
-<span id="L419" class="LineNr"> 419 </span>  <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, left
-<span id="L420" class="LineNr"> 420 </span>]
-<span id="L421" class="LineNr"> 421 </span>
-<span id="L422" class="LineNr"> 422 </span><span class="muScenario">scenario</span> read-text-wraps-barely-long-lines [
-<span id="L423" class="LineNr"> 423 </span>  <span class="Constant">local-scope</span>
-<span id="L424" class="LineNr"> 424 </span>  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
-<span id="L425" class="LineNr"> 425 </span>  s:text <span class="Special">&lt;-</span> new <span class="Constant">[abcde]</span>
-<span id="L426" class="LineNr"> 426 </span>  run [
-<span id="L427" class="LineNr"> 427 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L360'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, s, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>, <span class="Constant">7/white</span>, <span class="Constant">1/row</span>
-<span id="L428" class="LineNr"> 428 </span>  ]
-<span id="L429" class="LineNr"> 429 </span>  screen-should-contain [
-<span id="L430" class="LineNr"> 430 </span>  <span class="Conceal">¦</span><span class="Constant"> .     .</span>
-<span id="L431" class="LineNr"> 431 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .abcd↩.</span>
-<span id="L432" class="LineNr"> 432 </span>  <span class="Conceal">¦</span><span class="Constant"> .e    .</span>
-<span id="L433" class="LineNr"> 433 </span>  <span class="Conceal">¦</span><span class="Constant"> .     .</span>
+<span id="L419" class="LineNr"> 419 </span>  was-at-left?:bool <span class="Special">&lt;-</span> equal column, left
+<span id="L420" class="LineNr"> 420 </span>  <a href='../081print.mu.html#L536'>clear-line-until</a> <a href='../081print.mu.html#L4'>screen</a>, right
+<span id="L421" class="LineNr"> 421 </span>  <span class="Delimiter">{</span>
+<span id="L422" class="LineNr"> 422 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> was-at-left?
+<span id="L423" class="LineNr"> 423 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L424" class="LineNr"> 424 </span>  <span class="Delimiter">}</span>
+<span id="L425" class="LineNr"> 425 </span>  <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, left
+<span id="L426" class="LineNr"> 426 </span>]
+<span id="L427" class="LineNr"> 427 </span>
+<span id="L428" class="LineNr"> 428 </span><span class="muScenario">scenario</span> read-text-wraps-barely-long-lines [
+<span id="L429" class="LineNr"> 429 </span>  <span class="Constant">local-scope</span>
+<span id="L430" class="LineNr"> 430 </span>  assume-screen <span class="Constant">5/width</span>, <span class="Constant">5/height</span>
+<span id="L431" class="LineNr"> 431 </span>  s:text <span class="Special">&lt;-</span> new <span class="Constant">[abcde]</span>
+<span id="L432" class="LineNr"> 432 </span>  run [
+<span id="L433" class="LineNr"> 433 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L366'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, s, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>, <span class="Constant">7/white</span>, <span class="Constant">1/row</span>
 <span id="L434" class="LineNr"> 434 </span>  ]
-<span id="L435" class="LineNr"> 435 </span>]
-<span id="L436" class="LineNr"> 436 </span>
-<span id="L437" class="LineNr"> 437 </span><span class="Comment"># assumes programming environment has no sandboxes; restores them from previous session</span>
-<span id="L438" class="LineNr"> 438 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L438'>restore-sandboxes</a> env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a><span class="muRecipe"> -&gt; </span>env:&amp;:environment [
-<span id="L439" class="LineNr"> 439 </span>  <span class="Constant">local-scope</span>
-<span id="L440" class="LineNr"> 440 </span>  <span class="Constant">load-ingredients</span>
-<span id="L441" class="LineNr"> 441 </span>  <span class="Comment"># read all scenarios, pushing them to end of a list of scenarios</span>
-<span id="L442" class="LineNr"> 442 </span>  idx:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
-<span id="L443" class="LineNr"> 443 </span>  curr:&amp;:sandbox <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
-<span id="L444" class="LineNr"> 444 </span>  <a href='../065duplex_list.mu.html#L36'>prev</a>:&amp;:sandbox <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
-<span id="L445" class="LineNr"> 445 </span>  <span class="Delimiter">{</span>
-<span id="L446" class="LineNr"> 446 </span>  <span class="Conceal">¦</span> filename:text <span class="Special">&lt;-</span> append <span class="Constant">[lesson/]</span>, idx
-<span id="L447" class="LineNr"> 447 </span>  <span class="Conceal">¦</span> contents:text <span class="Special">&lt;-</span> <a href='../088file.mu.html#L38'>slurp</a> <a href='../088file.mu.html#L11'>resources</a>, filename
-<span id="L448" class="LineNr"> 448 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> contents  <span class="Comment"># stop at first error; assuming file didn't exist</span>
-<span id="L449" class="LineNr"> 449 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span>      <span class="Comment"># todo: handle empty sandbox</span>
-<span id="L450" class="LineNr"> 450 </span>  <span class="Conceal">¦</span> <span class="Comment"># create new sandbox for file</span>
-<span id="L451" class="LineNr"> 451 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> new <span class="Constant">sandbox:type</span>
-<span id="L452" class="LineNr"> 452 </span>  <span class="Conceal">¦</span> *curr <span class="Special">&lt;-</span> put *curr, <span class="Constant">data:offset</span>, contents
-<span id="L453" class="LineNr"> 453 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L453'>&lt;end-restore-sandbox&gt;</a></span>
-<span id="L454" class="LineNr"> 454 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L455" class="LineNr"> 455 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> idx
-<span id="L456" class="LineNr"> 456 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox:offset</span>, curr
-<span id="L457" class="LineNr"> 457 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L458" class="LineNr"> 458 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L459" class="LineNr"> 459 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> idx
-<span id="L460" class="LineNr"> 460 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> *prev <span class="Special">&lt;-</span> put *prev, <span class="Constant">next-sandbox:offset</span>, curr
-<span id="L461" class="LineNr"> 461 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L462" class="LineNr"> 462 </span>  <span class="Conceal">¦</span> idx <span class="Special">&lt;-</span> add idx,<span class="Constant"> 1</span>
-<span id="L463" class="LineNr"> 463 </span>  <span class="Conceal">¦</span> <a href='../065duplex_list.mu.html#L36'>prev</a> <span class="Special">&lt;-</span> copy curr
-<span id="L464" class="LineNr"> 464 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L465" class="LineNr"> 465 </span>  <span class="Delimiter">}</span>
-<span id="L466" class="LineNr"> 466 </span>  <span class="Comment"># update sandbox count</span>
-<span id="L467" class="LineNr"> 467 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">number-of-sandboxes:offset</span>, idx
-<span id="L468" class="LineNr"> 468 </span>]
-<span id="L469" class="LineNr"> 469 </span>
-<span id="L470" class="LineNr"> 470 </span><span class="Comment"># print the fake sandbox screen to 'screen' with appropriate delimiters</span>
-<span id="L471" class="LineNr"> 471 </span><span class="Comment"># leave cursor at start of next line</span>
-<span id="L472" class="LineNr"> 472 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L472'>render-screen</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, sandbox-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a>, left:num, right:num, row:num<span class="muRecipe"> -&gt; </span>row:num, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
-<span id="L473" class="LineNr"> 473 </span>  <span class="Constant">local-scope</span>
-<span id="L474" class="LineNr"> 474 </span>  <span class="Constant">load-ingredients</span>
-<span id="L475" class="LineNr"> 475 </span>  <span class="muControl">return-unless</span> sandbox-screen
-<span id="L476" class="LineNr"> 476 </span>  <span class="Comment"># print 'screen:'</span>
-<span id="L477" class="LineNr"> 477 </span>  row <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L360'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[screen:]</span>, left, right, <span class="Constant">245/grey</span>, row
-<span id="L478" class="LineNr"> 478 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, left
-<span id="L479" class="LineNr"> 479 </span>  <span class="Comment"># start printing sandbox-screen</span>
-<span id="L480" class="LineNr"> 480 </span>  column:num <span class="Special">&lt;-</span> copy left
-<span id="L481" class="LineNr"> 481 </span>  s-width:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L735'>screen-width</a> sandbox-screen
-<span id="L482" class="LineNr"> 482 </span>  s-height:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> sandbox-screen
-<span id="L483" class="LineNr"> 483 </span>  buf:&amp;:@:<a href='../081print.mu.html#L14'>screen-cell</a> <span class="Special">&lt;-</span> get *sandbox-screen, <span class="Constant">data:offset</span>
-<span id="L484" class="LineNr"> 484 </span>  stop-printing:num <span class="Special">&lt;-</span> add left, s-width,<span class="Constant"> 3</span>
-<span id="L485" class="LineNr"> 485 </span>  max-column:num <span class="Special">&lt;-</span> min stop-printing, right
-<span id="L486" class="LineNr"> 486 </span>  i:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
-<span id="L487" class="LineNr"> 487 </span>  len:num <span class="Special">&lt;-</span> length *buf
-<span id="L488" class="LineNr"> 488 </span>  <a href='../081print.mu.html#L748'>screen-height</a>:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> <a href='../081print.mu.html#L4'>screen</a>
-<span id="L489" class="LineNr"> 489 </span>  <span class="Delimiter">{</span>
-<span id="L490" class="LineNr"> 490 </span>  <span class="Conceal">¦</span> done?:bool <span class="Special">&lt;-</span> greater-or-equal i, len
-<span id="L491" class="LineNr"> 491 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
-<span id="L492" class="LineNr"> 492 </span>  <span class="Conceal">¦</span> done? <span class="Special">&lt;-</span> greater-or-equal row, <a href='../081print.mu.html#L748'>screen-height</a>
-<span id="L493" class="LineNr"> 493 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
-<span id="L494" class="LineNr"> 494 </span>  <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> copy left
-<span id="L495" class="LineNr"> 495 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, column
-<span id="L496" class="LineNr"> 496 </span>  <span class="Conceal">¦</span> <span class="Comment"># initial leader for each row: two spaces and a '.'</span>
-<span id="L497" class="LineNr"> 497 </span>  <span class="Conceal">¦</span> space:char <span class="Special">&lt;-</span> copy <span class="Constant">32/space</span>
-<span id="L498" class="LineNr"> 498 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, space, <span class="Constant">245/grey</span>
-<span id="L499" class="LineNr"> 499 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, space, <span class="Constant">245/grey</span>
-<span id="L500" class="LineNr"> 500 </span>  <span class="Conceal">¦</span> full-stop:char <span class="Special">&lt;-</span> copy <span class="Constant">46/period</span>
-<span id="L501" class="LineNr"> 501 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, full-stop, <span class="Constant">245/grey</span>
-<span id="L502" class="LineNr"> 502 </span>  <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add left,<span class="Constant"> 3</span>
-<span id="L503" class="LineNr"> 503 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L504" class="LineNr"> 504 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># print row</span>
-<span id="L505" class="LineNr"> 505 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row-done?:bool <span class="Special">&lt;-</span> greater-or-equal column, max-column
-<span id="L506" class="LineNr"> 506 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> row-done?
-<span id="L507" class="LineNr"> 507 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> curr:<a href='../081print.mu.html#L14'>screen-cell</a> <span class="Special">&lt;-</span> index *buf, i
-<span id="L508" class="LineNr"> 508 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> c:char <span class="Special">&lt;-</span> get curr, <span class="Constant">contents:offset</span>
-<span id="L509" class="LineNr"> 509 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> color:num <span class="Special">&lt;-</span> get curr, <span class="Constant">color:offset</span>
-<span id="L510" class="LineNr"> 510 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L511" class="LineNr"> 511 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># damp whites down to grey</span>
-<span id="L512" class="LineNr"> 512 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> white?:bool <span class="Special">&lt;-</span> equal color, <span class="Constant">7/white</span>
-<span id="L513" class="LineNr"> 513 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> white?
-<span id="L514" class="LineNr"> 514 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> color <span class="Special">&lt;-</span> copy <span class="Constant">245/grey</span>
-<span id="L515" class="LineNr"> 515 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L516" class="LineNr"> 516 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, c, color
-<span id="L517" class="LineNr"> 517 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
-<span id="L518" class="LineNr"> 518 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> i <span class="Special">&lt;-</span> add i,<span class="Constant"> 1</span>
-<span id="L519" class="LineNr"> 519 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L520" class="LineNr"> 520 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L521" class="LineNr"> 521 </span>  <span class="Conceal">¦</span> <span class="Comment"># print final '.'</span>
-<span id="L522" class="LineNr"> 522 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, full-stop, <span class="Constant">245/grey</span>
-<span id="L523" class="LineNr"> 523 </span>  <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
-<span id="L524" class="LineNr"> 524 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L525" class="LineNr"> 525 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># clear rest of current line</span>
-<span id="L526" class="LineNr"> 526 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> line-done?:bool <span class="Special">&lt;-</span> greater-than column, right
-<span id="L527" class="LineNr"> 527 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> line-done?
-<span id="L528" class="LineNr"> 528 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, space
-<span id="L529" class="LineNr"> 529 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
-<span id="L530" class="LineNr"> 530 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L531" class="LineNr"> 531 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L532" class="LineNr"> 532 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
-<span id="L533" class="LineNr"> 533 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L534" class="LineNr"> 534 </span>  <span class="Delimiter">}</span>
-<span id="L535" class="LineNr"> 535 </span>]
-<span id="L536" class="LineNr"> 536 </span>
-<span id="L537" class="LineNr"> 537 </span><span class="muScenario">scenario</span> run-updates-results [
-<span id="L538" class="LineNr"> 538 </span>  <span class="Constant">local-scope</span>
-<span id="L539" class="LineNr"> 539 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L540" class="LineNr"> 540 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">12/height</span>
-<span id="L541" class="LineNr"> 541 </span>  <span class="Comment"># define a recipe (no indent for the 'add' line below so column numbers are more obvious)</span>
-<span id="L542" class="LineNr"> 542 </span>  assume-resources [
-<span id="L543" class="LineNr"> 543 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
-<span id="L544" class="LineNr"> 544 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> ||</span>
-<span id="L545" class="LineNr"> 545 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
-<span id="L546" class="LineNr"> 546 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  local-scope|</span>
-<span id="L547" class="LineNr"> 547 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  z:num &lt;- add 2, 2|</span>
-<span id="L548" class="LineNr"> 548 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  reply z|</span>
-<span id="L549" class="LineNr"> 549 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
-<span id="L550" class="LineNr"> 550 </span>  <span class="Conceal">¦</span> ]
-<span id="L551" class="LineNr"> 551 </span>  ]
-<span id="L552" class="LineNr"> 552 </span>  <span class="Comment"># sandbox editor contains an instruction without storing outputs</span>
-<span id="L553" class="LineNr"> 553 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>  <span class="Comment"># contents of sandbox editor</span>
-<span id="L554" class="LineNr"> 554 </span>  <span class="Comment"># run the code in the editors</span>
-<span id="L555" class="LineNr"> 555 </span>  assume-console [
-<span id="L556" class="LineNr"> 556 </span>  <span class="Conceal">¦</span> press F4
+<span id="L435" class="LineNr"> 435 </span>  screen-should-contain [
+<span id="L436" class="LineNr"> 436 </span>  <span class="Conceal">¦</span><span class="Constant"> .     .</span>
+<span id="L437" class="LineNr"> 437 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .abcd↩.</span>
+<span id="L438" class="LineNr"> 438 </span>  <span class="Conceal">¦</span><span class="Constant"> .e    .</span>
+<span id="L439" class="LineNr"> 439 </span>  <span class="Conceal">¦</span><span class="Constant"> .     .</span>
+<span id="L440" class="LineNr"> 440 </span>  ]
+<span id="L441" class="LineNr"> 441 </span>]
+<span id="L442" class="LineNr"> 442 </span>
+<span id="L443" class="LineNr"> 443 </span><span class="Comment"># assumes programming environment has no sandboxes; restores them from previous session</span>
+<span id="L444" class="LineNr"> 444 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L444'>restore-sandboxes</a> env:&amp;:environment, <a href='../088file.mu.html#L11'>resources</a>:&amp;:<a href='../088file.mu.html#L11'>resources</a><span class="muRecipe"> -&gt; </span>env:&amp;:environment [
+<span id="L445" class="LineNr"> 445 </span>  <span class="Constant">local-scope</span>
+<span id="L446" class="LineNr"> 446 </span>  <span class="Constant">load-ingredients</span>
+<span id="L447" class="LineNr"> 447 </span>  <span class="Comment"># read all scenarios, pushing them to end of a list of scenarios</span>
+<span id="L448" class="LineNr"> 448 </span>  idx:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
+<span id="L449" class="LineNr"> 449 </span>  curr:&amp;:sandbox <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
+<span id="L450" class="LineNr"> 450 </span>  <a href='../065duplex_list.mu.html#L36'>prev</a>:&amp;:sandbox <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
+<span id="L451" class="LineNr"> 451 </span>  <span class="Delimiter">{</span>
+<span id="L452" class="LineNr"> 452 </span>  <span class="Conceal">¦</span> filename:text <span class="Special">&lt;-</span> append <span class="Constant">[lesson/]</span>, idx
+<span id="L453" class="LineNr"> 453 </span>  <span class="Conceal">¦</span> contents:text <span class="Special">&lt;-</span> <a href='../088file.mu.html#L38'>slurp</a> <a href='../088file.mu.html#L11'>resources</a>, filename
+<span id="L454" class="LineNr"> 454 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> contents  <span class="Comment"># stop at first error; assuming file didn't exist</span>
+<span id="L455" class="LineNr"> 455 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span>      <span class="Comment"># todo: handle empty sandbox</span>
+<span id="L456" class="LineNr"> 456 </span>  <span class="Conceal">¦</span> <span class="Comment"># create new sandbox for file</span>
+<span id="L457" class="LineNr"> 457 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> new <span class="Constant">sandbox:type</span>
+<span id="L458" class="LineNr"> 458 </span>  <span class="Conceal">¦</span> *curr <span class="Special">&lt;-</span> put *curr, <span class="Constant">data:offset</span>, contents
+<span id="L459" class="LineNr"> 459 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> <a href='005-sandbox.mu.html#L459'>&lt;end-restore-sandbox&gt;</a></span>
+<span id="L460" class="LineNr"> 460 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L461" class="LineNr"> 461 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> idx
+<span id="L462" class="LineNr"> 462 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox:offset</span>, curr
+<span id="L463" class="LineNr"> 463 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L464" class="LineNr"> 464 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L465" class="LineNr"> 465 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> idx
+<span id="L466" class="LineNr"> 466 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> *prev <span class="Special">&lt;-</span> put *prev, <span class="Constant">next-sandbox:offset</span>, curr
+<span id="L467" class="LineNr"> 467 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L468" class="LineNr"> 468 </span>  <span class="Conceal">¦</span> idx <span class="Special">&lt;-</span> add idx,<span class="Constant"> 1</span>
+<span id="L469" class="LineNr"> 469 </span>  <span class="Conceal">¦</span> <a href='../065duplex_list.mu.html#L36'>prev</a> <span class="Special">&lt;-</span> copy curr
+<span id="L470" class="LineNr"> 470 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L471" class="LineNr"> 471 </span>  <span class="Delimiter">}</span>
+<span id="L472" class="LineNr"> 472 </span>  <span class="Comment"># update sandbox count</span>
+<span id="L473" class="LineNr"> 473 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">number-of-sandboxes:offset</span>, idx
+<span id="L474" class="LineNr"> 474 </span>]
+<span id="L475" class="LineNr"> 475 </span>
+<span id="L476" class="LineNr"> 476 </span><span class="Comment"># print the fake sandbox screen to 'screen' with appropriate delimiters</span>
+<span id="L477" class="LineNr"> 477 </span><span class="Comment"># leave cursor at start of next line</span>
+<span id="L478" class="LineNr"> 478 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L478'>render-screen</a> <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a>, sandbox-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a>, left:num, right:num, row:num<span class="muRecipe"> -&gt; </span>row:num, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a> [
+<span id="L479" class="LineNr"> 479 </span>  <span class="Constant">local-scope</span>
+<span id="L480" class="LineNr"> 480 </span>  <span class="Constant">load-ingredients</span>
+<span id="L481" class="LineNr"> 481 </span>  <span class="muControl">return-unless</span> sandbox-screen
+<span id="L482" class="LineNr"> 482 </span>  <span class="Comment"># print 'screen:'</span>
+<span id="L483" class="LineNr"> 483 </span>  row <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L366'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[screen:]</span>, left, right, <span class="Constant">245/grey</span>, row
+<span id="L484" class="LineNr"> 484 </span>  <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, left
+<span id="L485" class="LineNr"> 485 </span>  <span class="Comment"># start printing sandbox-screen</span>
+<span id="L486" class="LineNr"> 486 </span>  column:num <span class="Special">&lt;-</span> copy left
+<span id="L487" class="LineNr"> 487 </span>  s-width:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L735'>screen-width</a> sandbox-screen
+<span id="L488" class="LineNr"> 488 </span>  s-height:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> sandbox-screen
+<span id="L489" class="LineNr"> 489 </span>  buf:&amp;:@:<a href='../081print.mu.html#L14'>screen-cell</a> <span class="Special">&lt;-</span> get *sandbox-screen, <span class="Constant">data:offset</span>
+<span id="L490" class="LineNr"> 490 </span>  stop-printing:num <span class="Special">&lt;-</span> add left, s-width,<span class="Constant"> 3</span>
+<span id="L491" class="LineNr"> 491 </span>  max-column:num <span class="Special">&lt;-</span> min stop-printing, right
+<span id="L492" class="LineNr"> 492 </span>  i:num <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
+<span id="L493" class="LineNr"> 493 </span>  len:num <span class="Special">&lt;-</span> length *buf
+<span id="L494" class="LineNr"> 494 </span>  <a href='../081print.mu.html#L748'>screen-height</a>:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> <a href='../081print.mu.html#L4'>screen</a>
+<span id="L495" class="LineNr"> 495 </span>  <span class="Delimiter">{</span>
+<span id="L496" class="LineNr"> 496 </span>  <span class="Conceal">¦</span> done?:bool <span class="Special">&lt;-</span> greater-or-equal i, len
+<span id="L497" class="LineNr"> 497 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
+<span id="L498" class="LineNr"> 498 </span>  <span class="Conceal">¦</span> done? <span class="Special">&lt;-</span> greater-or-equal row, <a href='../081print.mu.html#L748'>screen-height</a>
+<span id="L499" class="LineNr"> 499 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> done?
+<span id="L500" class="LineNr"> 500 </span>  <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> copy left
+<span id="L501" class="LineNr"> 501 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, row, column
+<span id="L502" class="LineNr"> 502 </span>  <span class="Conceal">¦</span> <span class="Comment"># initial leader for each row: two spaces and a '.'</span>
+<span id="L503" class="LineNr"> 503 </span>  <span class="Conceal">¦</span> space:char <span class="Special">&lt;-</span> copy <span class="Constant">32/space</span>
+<span id="L504" class="LineNr"> 504 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, space, <span class="Constant">245/grey</span>
+<span id="L505" class="LineNr"> 505 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, space, <span class="Constant">245/grey</span>
+<span id="L506" class="LineNr"> 506 </span>  <span class="Conceal">¦</span> full-stop:char <span class="Special">&lt;-</span> copy <span class="Constant">46/period</span>
+<span id="L507" class="LineNr"> 507 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, full-stop, <span class="Constant">245/grey</span>
+<span id="L508" class="LineNr"> 508 </span>  <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add left,<span class="Constant"> 3</span>
+<span id="L509" class="LineNr"> 509 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L510" class="LineNr"> 510 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># print row</span>
+<span id="L511" class="LineNr"> 511 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row-done?:bool <span class="Special">&lt;-</span> greater-or-equal column, max-column
+<span id="L512" class="LineNr"> 512 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> row-done?
+<span id="L513" class="LineNr"> 513 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> curr:<a href='../081print.mu.html#L14'>screen-cell</a> <span class="Special">&lt;-</span> index *buf, i
+<span id="L514" class="LineNr"> 514 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> c:char <span class="Special">&lt;-</span> get curr, <span class="Constant">contents:offset</span>
+<span id="L515" class="LineNr"> 515 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> color:num <span class="Special">&lt;-</span> get curr, <span class="Constant">color:offset</span>
+<span id="L516" class="LineNr"> 516 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L517" class="LineNr"> 517 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># damp whites down to grey</span>
+<span id="L518" class="LineNr"> 518 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> white?:bool <span class="Special">&lt;-</span> equal color, <span class="Constant">7/white</span>
+<span id="L519" class="LineNr"> 519 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> white?
+<span id="L520" class="LineNr"> 520 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Conceal">¦</span> color <span class="Special">&lt;-</span> copy <span class="Constant">245/grey</span>
+<span id="L521" class="LineNr"> 521 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L522" class="LineNr"> 522 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, c, color
+<span id="L523" class="LineNr"> 523 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
+<span id="L524" class="LineNr"> 524 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> i <span class="Special">&lt;-</span> add i,<span class="Constant"> 1</span>
+<span id="L525" class="LineNr"> 525 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L526" class="LineNr"> 526 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L527" class="LineNr"> 527 </span>  <span class="Conceal">¦</span> <span class="Comment"># print final '.'</span>
+<span id="L528" class="LineNr"> 528 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, full-stop, <span class="Constant">245/grey</span>
+<span id="L529" class="LineNr"> 529 </span>  <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
+<span id="L530" class="LineNr"> 530 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L531" class="LineNr"> 531 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Comment"># clear rest of current line</span>
+<span id="L532" class="LineNr"> 532 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> line-done?:bool <span class="Special">&lt;-</span> greater-than column, right
+<span id="L533" class="LineNr"> 533 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> line-done?
+<span id="L534" class="LineNr"> 534 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, space
+<span id="L535" class="LineNr"> 535 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> column <span class="Special">&lt;-</span> add column,<span class="Constant"> 1</span>
+<span id="L536" class="LineNr"> 536 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L537" class="LineNr"> 537 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L538" class="LineNr"> 538 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L539" class="LineNr"> 539 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L540" class="LineNr"> 540 </span>  <span class="Delimiter">}</span>
+<span id="L541" class="LineNr"> 541 </span>]
+<span id="L542" class="LineNr"> 542 </span>
+<span id="L543" class="LineNr"> 543 </span><span class="muScenario">scenario</span> run-updates-results [
+<span id="L544" class="LineNr"> 544 </span>  <span class="Constant">local-scope</span>
+<span id="L545" class="LineNr"> 545 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L546" class="LineNr"> 546 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">12/height</span>
+<span id="L547" class="LineNr"> 547 </span>  <span class="Comment"># define a recipe (no indent for the 'add' line below so column numbers are more obvious)</span>
+<span id="L548" class="LineNr"> 548 </span>  assume-resources [
+<span id="L549" class="LineNr"> 549 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L550" class="LineNr"> 550 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> ||</span>
+<span id="L551" class="LineNr"> 551 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
+<span id="L552" class="LineNr"> 552 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  local-scope|</span>
+<span id="L553" class="LineNr"> 553 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  z:num &lt;- add 2, 2|</span>
+<span id="L554" class="LineNr"> 554 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  reply z|</span>
+<span id="L555" class="LineNr"> 555 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
+<span id="L556" class="LineNr"> 556 </span>  <span class="Conceal">¦</span> ]
 <span id="L557" class="LineNr"> 557 </span>  ]
-<span id="L558" class="LineNr"> 558 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L559" class="LineNr"> 559 </span>  screen-should-contain [
-<span id="L560" class="LineNr"> 560 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L561" class="LineNr"> 561 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L562" class="LineNr"> 562 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎─────────────────────────────────────────────────.</span>
-<span id="L563" class="LineNr"> 563 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L564" class="LineNr"> 564 </span>  <span class="Conceal">¦</span><span class="Constant"> .  z:num &lt;- add 2, 2                               ╎foo                                              .</span>
-<span id="L565" class="LineNr"> 565 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply z                                         ╎4                                                .</span>
-<span id="L566" class="LineNr"> 566 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎─────────────────────────────────────────────────.</span>
-<span id="L567" class="LineNr"> 567 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L568" class="LineNr"> 568 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L558" class="LineNr"> 558 </span>  <span class="Comment"># sandbox editor contains an instruction without storing outputs</span>
+<span id="L559" class="LineNr"> 559 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>  <span class="Comment"># contents of sandbox editor</span>
+<span id="L560" class="LineNr"> 560 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L561" class="LineNr"> 561 </span>  $clear-trace
+<span id="L562" class="LineNr"> 562 </span>  <span class="Comment"># run the code in the editors</span>
+<span id="L563" class="LineNr"> 563 </span>  assume-console [
+<span id="L564" class="LineNr"> 564 </span>  <span class="Conceal">¦</span> press F4
+<span id="L565" class="LineNr"> 565 </span>  ]
+<span id="L566" class="LineNr"> 566 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L567" class="LineNr"> 567 </span>  screen-should-contain [
+<span id="L568" class="LineNr"> 568 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
 <span id="L569" class="LineNr"> 569 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L570" class="LineNr"> 570 </span>  ]
-<span id="L571" class="LineNr"> 571 </span>  <span class="Comment"># make a change (incrementing one of the args to 'add'), then rerun</span>
-<span id="L572" class="LineNr"> 572 </span>  assume-console [
-<span id="L573" class="LineNr"> 573 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 28</span>  <span class="Comment"># one past the value of the second arg</span>
-<span id="L574" class="LineNr"> 574 </span>  <span class="Conceal">¦</span> press backspace
-<span id="L575" class="LineNr"> 575 </span>  <span class="Conceal">¦</span> type <span class="Constant">[3]</span>
-<span id="L576" class="LineNr"> 576 </span>  <span class="Conceal">¦</span> press F4
-<span id="L577" class="LineNr"> 577 </span>  ]
-<span id="L578" class="LineNr"> 578 </span>  run [
-<span id="L579" class="LineNr"> 579 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L580" class="LineNr"> 580 </span>  ]
-<span id="L581" class="LineNr"> 581 </span>  <span class="Comment"># check that screen updates the result on the right</span>
-<span id="L582" class="LineNr"> 582 </span>  screen-should-contain [
-<span id="L583" class="LineNr"> 583 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L584" class="LineNr"> 584 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L585" class="LineNr"> 585 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎─────────────────────────────────────────────────.</span>
-<span id="L586" class="LineNr"> 586 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L587" class="LineNr"> 587 </span>  <span class="Conceal">¦</span><span class="Constant"> .  z:num &lt;- add 2, 3                               ╎foo                                              .</span>
-<span id="L588" class="LineNr"> 588 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply z                                         ╎5                                                .</span>
-<span id="L589" class="LineNr"> 589 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎─────────────────────────────────────────────────.</span>
-<span id="L590" class="LineNr"> 590 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L591" class="LineNr"> 591 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L592" class="LineNr"> 592 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L593" class="LineNr"> 593 </span>  ]
-<span id="L594" class="LineNr"> 594 </span>]
-<span id="L595" class="LineNr"> 595 </span>
-<span id="L596" class="LineNr"> 596 </span><span class="muScenario">scenario</span> run-instruction-manages-screen-per-sandbox [
-<span id="L597" class="LineNr"> 597 </span>  <span class="Constant">local-scope</span>
-<span id="L598" class="LineNr"> 598 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L599" class="LineNr"> 599 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">20/height</span>
-<span id="L600" class="LineNr"> 600 </span>  <span class="Comment"># empty recipes</span>
-<span id="L601" class="LineNr"> 601 </span>  assume-resources [
-<span id="L602" class="LineNr"> 602 </span>  ]
-<span id="L603" class="LineNr"> 603 </span>  <span class="Comment"># sandbox editor contains an instruction</span>
-<span id="L604" class="LineNr"> 604 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[print <a href='../081print.mu.html#L4'>screen</a>, 4]</span>  <span class="Comment"># contents of sandbox editor</span>
-<span id="L605" class="LineNr"> 605 </span>  <span class="Comment"># run the code in the editor</span>
-<span id="L606" class="LineNr"> 606 </span>  assume-console [
-<span id="L607" class="LineNr"> 607 </span>  <span class="Conceal">¦</span> press F4
-<span id="L608" class="LineNr"> 608 </span>  ]
-<span id="L609" class="LineNr"> 609 </span>  run [
-<span id="L610" class="LineNr"> 610 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L611" class="LineNr"> 611 </span>  ]
-<span id="L612" class="LineNr"> 612 </span>  <span class="Comment"># check that it prints a little toy screen</span>
-<span id="L613" class="LineNr"> 613 </span>  screen-should-contain [
-<span id="L614" class="LineNr"> 614 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L615" class="LineNr"> 615 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L616" class="LineNr"> 616 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L617" class="LineNr"> 617 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L618" class="LineNr"> 618 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎print <a href='../081print.mu.html#L4'>screen</a>, 4                                  .</span>
-<span id="L619" class="LineNr"> 619 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎screen:                                          .</span>
-<span id="L620" class="LineNr"> 620 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .4                             .               .</span>
-<span id="L621" class="LineNr"> 621 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
-<span id="L622" class="LineNr"> 622 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
-<span id="L623" class="LineNr"> 623 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
-<span id="L624" class="LineNr"> 624 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
-<span id="L625" class="LineNr"> 625 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L626" class="LineNr"> 626 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L627" class="LineNr"> 627 </span>  ]
-<span id="L628" class="LineNr"> 628 </span>]
-<span id="L629" class="LineNr"> 629 </span>
-<span id="L630" class="LineNr"> 630 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L630'>editor-contents</a> editor:&amp;:editor<span class="muRecipe"> -&gt; </span>result:text [
-<span id="L631" class="LineNr"> 631 </span>  <span class="Constant">local-scope</span>
-<span id="L632" class="LineNr"> 632 </span>  <span class="Constant">load-ingredients</span>
-<span id="L633" class="LineNr"> 633 </span>  buf:&amp;:<a href='../061text.mu.html#L126'>buffer</a>:char <span class="Special">&lt;-</span> <a href='../061text.mu.html#L131'>new-buffer</a><span class="Constant"> 80</span>
-<span id="L634" class="LineNr"> 634 </span>  curr:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> get *editor, <span class="Constant">data:offset</span>
-<span id="L635" class="LineNr"> 635 </span>  <span class="Comment"># skip § sentinel</span>
-<span id="L636" class="LineNr"> 636 </span>  assert curr, <span class="Constant">[editor without data is illegal; must have at least a sentinel]</span>
-<span id="L637" class="LineNr"> 637 </span>  curr <span class="Special">&lt;-</span> <a href='../065duplex_list.mu.html#L29'>next</a> curr
-<span id="L638" class="LineNr"> 638 </span>  <span class="muControl">return-unless</span> curr,<span class="Constant"> 0</span>
-<span id="L639" class="LineNr"> 639 </span>  <span class="Delimiter">{</span>
-<span id="L640" class="LineNr"> 640 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> curr
-<span id="L641" class="LineNr"> 641 </span>  <span class="Conceal">¦</span> c:char <span class="Special">&lt;-</span> get *curr, <span class="Constant">value:offset</span>
-<span id="L642" class="LineNr"> 642 </span>  <span class="Conceal">¦</span> buf <span class="Special">&lt;-</span> append buf, c
-<span id="L643" class="LineNr"> 643 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> <a href='../065duplex_list.mu.html#L29'>next</a> curr
-<span id="L644" class="LineNr"> 644 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L645" class="LineNr"> 645 </span>  <span class="Delimiter">}</span>
-<span id="L646" class="LineNr"> 646 </span>  result <span class="Special">&lt;-</span> <a href='../061text.mu.html#L344'>buffer-to-array</a> buf
-<span id="L647" class="LineNr"> 647 </span>]
-<span id="L648" class="LineNr"> 648 </span>
-<span id="L649" class="LineNr"> 649 </span><span class="muScenario">scenario</span> editor-provides-edited-contents [
-<span id="L650" class="LineNr"> 650 </span>  <span class="Constant">local-scope</span>
-<span id="L651" class="LineNr"> 651 </span>  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-<span id="L652" class="LineNr"> 652 </span>  e:&amp;:editor <span class="Special">&lt;-</span> <a href='001-editor.mu.html#L51'>new-editor</a> <span class="Constant">[abc]</span>, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-<span id="L653" class="LineNr"> 653 </span>  assume-console [
-<span id="L654" class="LineNr"> 654 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 1</span>,<span class="Constant"> 2</span>
-<span id="L655" class="LineNr"> 655 </span>  <span class="Conceal">¦</span> type <span class="Constant">[def]</span>
-<span id="L656" class="LineNr"> 656 </span>  ]
-<span id="L657" class="LineNr"> 657 </span>  run [
-<span id="L658" class="LineNr"> 658 </span>  <span class="Conceal">¦</span> <a href='002-typing.mu.html#L16'>editor-event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, e
-<span id="L659" class="LineNr"> 659 </span>  <span class="Conceal">¦</span> s:text <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L630'>editor-contents</a> e
-<span id="L660" class="LineNr"> 660 </span>  <span class="Conceal">¦</span> 1:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s
-<span id="L661" class="LineNr"> 661 </span>  ]
-<span id="L662" class="LineNr"> 662 </span>  memory-should-contain [
-<span id="L663" class="LineNr"> 663 </span>  <span class="Conceal">¦</span> 1:array:character <span class="Special">&lt;-</span> <span class="Constant">[abdefc]</span>
-<span id="L664" class="LineNr"> 664 </span>  ]
-<span id="L665" class="LineNr"> 665 </span>]
-<span id="L666" class="LineNr"> 666 </span>
-<span id="L667" class="LineNr"> 667 </span><span class="Comment"># keep the bottom of recipes from scrolling off the screen</span>
-<span id="L668" class="LineNr"> 668 </span>
-<span id="L669" class="LineNr"> 669 </span><span class="muScenario">scenario</span> scrolling-down-past-bottom-of-recipe-editor [
-<span id="L670" class="LineNr"> 670 </span>  <span class="Constant">local-scope</span>
-<span id="L671" class="LineNr"> 671 </span>  trace-until <span class="Constant">100/app</span>
-<span id="L672" class="LineNr"> 672 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L673" class="LineNr"> 673 </span>  assume-resources [
+<span id="L570" class="LineNr"> 570 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎─────────────────────────────────────────────────.</span>
+<span id="L571" class="LineNr"> 571 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L572" class="LineNr"> 572 </span>  <span class="Conceal">¦</span><span class="Constant"> .  z:num &lt;- add 2, 2                               ╎foo                                              .</span>
+<span id="L573" class="LineNr"> 573 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply z                                         ╎4                                                .</span>
+<span id="L574" class="LineNr"> 574 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎─────────────────────────────────────────────────.</span>
+<span id="L575" class="LineNr"> 575 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L576" class="LineNr"> 576 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L577" class="LineNr"> 577 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L578" class="LineNr"> 578 </span>  ]
+<span id="L579" class="LineNr"> 579 </span>  <span class="Comment"># no need to update editor</span>
+<span id="L580" class="LineNr"> 580 </span>  trace-should-not-contain [
+<span id="L581" class="LineNr"> 581 </span>  <span class="Conceal">¦</span> app: <a href='001-editor.mu.html#L107'>render</a> recipes
+<span id="L582" class="LineNr"> 582 </span>  ]
+<span id="L583" class="LineNr"> 583 </span>  <span class="Comment"># make a change (incrementing one of the args to 'add'), then rerun</span>
+<span id="L584" class="LineNr"> 584 </span>  assume-console [
+<span id="L585" class="LineNr"> 585 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 28</span>  <span class="Comment"># one past the value of the second arg</span>
+<span id="L586" class="LineNr"> 586 </span>  <span class="Conceal">¦</span> press backspace
+<span id="L587" class="LineNr"> 587 </span>  <span class="Conceal">¦</span> type <span class="Constant">[3]</span>
+<span id="L588" class="LineNr"> 588 </span>  <span class="Conceal">¦</span> press F4
+<span id="L589" class="LineNr"> 589 </span>  ]
+<span id="L590" class="LineNr"> 590 </span>  run [
+<span id="L591" class="LineNr"> 591 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L592" class="LineNr"> 592 </span>  ]
+<span id="L593" class="LineNr"> 593 </span>  <span class="Comment"># check that screen updates the result on the right</span>
+<span id="L594" class="LineNr"> 594 </span>  screen-should-contain [
+<span id="L595" class="LineNr"> 595 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L596" class="LineNr"> 596 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L597" class="LineNr"> 597 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎─────────────────────────────────────────────────.</span>
+<span id="L598" class="LineNr"> 598 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L599" class="LineNr"> 599 </span>  <span class="Conceal">¦</span><span class="Constant"> .  z:num &lt;- add 2, 3                               ╎foo                                              .</span>
+<span id="L600" class="LineNr"> 600 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply z                                         ╎5                                                .</span>
+<span id="L601" class="LineNr"> 601 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎─────────────────────────────────────────────────.</span>
+<span id="L602" class="LineNr"> 602 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L603" class="LineNr"> 603 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L604" class="LineNr"> 604 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L605" class="LineNr"> 605 </span>  ]
+<span id="L606" class="LineNr"> 606 </span>]
+<span id="L607" class="LineNr"> 607 </span>
+<span id="L608" class="LineNr"> 608 </span><span class="muScenario">scenario</span> run-instruction-manages-screen-per-sandbox [
+<span id="L609" class="LineNr"> 609 </span>  <span class="Constant">local-scope</span>
+<span id="L610" class="LineNr"> 610 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L611" class="LineNr"> 611 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">20/height</span>
+<span id="L612" class="LineNr"> 612 </span>  <span class="Comment"># empty recipes</span>
+<span id="L613" class="LineNr"> 613 </span>  assume-resources [
+<span id="L614" class="LineNr"> 614 </span>  ]
+<span id="L615" class="LineNr"> 615 </span>  <span class="Comment"># sandbox editor contains an instruction</span>
+<span id="L616" class="LineNr"> 616 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[print <a href='../081print.mu.html#L4'>screen</a>, 4]</span>  <span class="Comment"># contents of sandbox editor</span>
+<span id="L617" class="LineNr"> 617 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L618" class="LineNr"> 618 </span>  <span class="Comment"># run the code in the editor</span>
+<span id="L619" class="LineNr"> 619 </span>  assume-console [
+<span id="L620" class="LineNr"> 620 </span>  <span class="Conceal">¦</span> press F4
+<span id="L621" class="LineNr"> 621 </span>  ]
+<span id="L622" class="LineNr"> 622 </span>  run [
+<span id="L623" class="LineNr"> 623 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L624" class="LineNr"> 624 </span>  ]
+<span id="L625" class="LineNr"> 625 </span>  <span class="Comment"># check that it prints a little toy screen</span>
+<span id="L626" class="LineNr"> 626 </span>  screen-should-contain [
+<span id="L627" class="LineNr"> 627 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L628" class="LineNr"> 628 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L629" class="LineNr"> 629 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L630" class="LineNr"> 630 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L631" class="LineNr"> 631 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎print <a href='../081print.mu.html#L4'>screen</a>, 4                                  .</span>
+<span id="L632" class="LineNr"> 632 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎screen:                                          .</span>
+<span id="L633" class="LineNr"> 633 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .4                             .               .</span>
+<span id="L634" class="LineNr"> 634 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
+<span id="L635" class="LineNr"> 635 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
+<span id="L636" class="LineNr"> 636 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
+<span id="L637" class="LineNr"> 637 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
+<span id="L638" class="LineNr"> 638 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L639" class="LineNr"> 639 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L640" class="LineNr"> 640 </span>  ]
+<span id="L641" class="LineNr"> 641 </span>]
+<span id="L642" class="LineNr"> 642 </span>
+<span id="L643" class="LineNr"> 643 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L643'>editor-contents</a> editor:&amp;:editor<span class="muRecipe"> -&gt; </span>result:text [
+<span id="L644" class="LineNr"> 644 </span>  <span class="Constant">local-scope</span>
+<span id="L645" class="LineNr"> 645 </span>  <span class="Constant">load-ingredients</span>
+<span id="L646" class="LineNr"> 646 </span>  buf:&amp;:<a href='../061text.mu.html#L126'>buffer</a>:char <span class="Special">&lt;-</span> <a href='../061text.mu.html#L131'>new-buffer</a><span class="Constant"> 80</span>
+<span id="L647" class="LineNr"> 647 </span>  curr:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> get *editor, <span class="Constant">data:offset</span>
+<span id="L648" class="LineNr"> 648 </span>  <span class="Comment"># skip § sentinel</span>
+<span id="L649" class="LineNr"> 649 </span>  assert curr, <span class="Constant">[editor without data is illegal; must have at least a sentinel]</span>
+<span id="L650" class="LineNr"> 650 </span>  curr <span class="Special">&lt;-</span> <a href='../065duplex_list.mu.html#L29'>next</a> curr
+<span id="L651" class="LineNr"> 651 </span>  <span class="muControl">return-unless</span> curr,<span class="Constant"> 0</span>
+<span id="L652" class="LineNr"> 652 </span>  <span class="Delimiter">{</span>
+<span id="L653" class="LineNr"> 653 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> curr
+<span id="L654" class="LineNr"> 654 </span>  <span class="Conceal">¦</span> c:char <span class="Special">&lt;-</span> get *curr, <span class="Constant">value:offset</span>
+<span id="L655" class="LineNr"> 655 </span>  <span class="Conceal">¦</span> buf <span class="Special">&lt;-</span> append buf, c
+<span id="L656" class="LineNr"> 656 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> <a href='../065duplex_list.mu.html#L29'>next</a> curr
+<span id="L657" class="LineNr"> 657 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L658" class="LineNr"> 658 </span>  <span class="Delimiter">}</span>
+<span id="L659" class="LineNr"> 659 </span>  result <span class="Special">&lt;-</span> <a href='../061text.mu.html#L344'>buffer-to-array</a> buf
+<span id="L660" class="LineNr"> 660 </span>]
+<span id="L661" class="LineNr"> 661 </span>
+<span id="L662" class="LineNr"> 662 </span><span class="muScenario">scenario</span> editor-provides-edited-contents [
+<span id="L663" class="LineNr"> 663 </span>  <span class="Constant">local-scope</span>
+<span id="L664" class="LineNr"> 664 </span>  assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
+<span id="L665" class="LineNr"> 665 </span>  e:&amp;:editor <span class="Special">&lt;-</span> <a href='001-editor.mu.html#L51'>new-editor</a> <span class="Constant">[abc]</span>, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+<span id="L666" class="LineNr"> 666 </span>  assume-console [
+<span id="L667" class="LineNr"> 667 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 1</span>,<span class="Constant"> 2</span>
+<span id="L668" class="LineNr"> 668 </span>  <span class="Conceal">¦</span> type <span class="Constant">[def]</span>
+<span id="L669" class="LineNr"> 669 </span>  ]
+<span id="L670" class="LineNr"> 670 </span>  run [
+<span id="L671" class="LineNr"> 671 </span>  <span class="Conceal">¦</span> <a href='002-typing.mu.html#L16'>editor-event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, e
+<span id="L672" class="LineNr"> 672 </span>  <span class="Conceal">¦</span> s:text <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L643'>editor-contents</a> e
+<span id="L673" class="LineNr"> 673 </span>  <span class="Conceal">¦</span> 1:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s
 <span id="L674" class="LineNr"> 674 </span>  ]
-<span id="L675" class="LineNr"> 675 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L676" class="LineNr"> 676 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L677" class="LineNr"> 677 </span>  assume-console [
-<span id="L678" class="LineNr"> 678 </span>  <span class="Conceal">¦</span> press enter
-<span id="L679" class="LineNr"> 679 </span>  <span class="Conceal">¦</span> press down-arrow
-<span id="L680" class="LineNr"> 680 </span>  ]
-<span id="L681" class="LineNr"> 681 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L682" class="LineNr"> 682 </span>  <span class="Comment"># no scroll</span>
-<span id="L683" class="LineNr"> 683 </span>  screen-should-contain [
-<span id="L684" class="LineNr"> 684 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L685" class="LineNr"> 685 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L686" class="LineNr"> 686 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L687" class="LineNr"> 687 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L688" class="LineNr"> 688 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L689" class="LineNr"> 689 </span>  ]
-<span id="L690" class="LineNr"> 690 </span>]
-<span id="L691" class="LineNr"> 691 </span>
-<span id="L692" class="LineNr"> 692 </span><span class="muScenario">scenario</span> cursor-down-in-recipe-editor [
-<span id="L693" class="LineNr"> 693 </span>  <span class="Constant">local-scope</span>
-<span id="L694" class="LineNr"> 694 </span>  trace-until <span class="Constant">100/app</span>
-<span id="L695" class="LineNr"> 695 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L696" class="LineNr"> 696 </span>  assume-resources [
-<span id="L697" class="LineNr"> 697 </span>  ]
-<span id="L698" class="LineNr"> 698 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L699" class="LineNr"> 699 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L700" class="LineNr"> 700 </span>  assume-console [
-<span id="L701" class="LineNr"> 701 </span>  <span class="Conceal">¦</span> press enter
-<span id="L702" class="LineNr"> 702 </span>  <span class="Conceal">¦</span> press up-arrow
-<span id="L703" class="LineNr"> 703 </span>  <span class="Conceal">¦</span> press down-arrow  <span class="Comment"># while cursor isn't at bottom</span>
-<span id="L704" class="LineNr"> 704 </span>  ]
-<span id="L705" class="LineNr"> 705 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L706" class="LineNr"> 706 </span>  cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L707" class="LineNr"> 707 </span>  print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L708" class="LineNr"> 708 </span>  <span class="Comment"># cursor moves back to bottom</span>
-<span id="L709" class="LineNr"> 709 </span>  screen-should-contain [
-<span id="L710" class="LineNr"> 710 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L711" class="LineNr"> 711 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L712" class="LineNr"> 712 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣                                                 ╎─────────────────────────────────────────────────.</span>
-<span id="L713" class="LineNr"> 713 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L714" class="LineNr"> 714 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L715" class="LineNr"> 715 </span>  ]
-<span id="L716" class="LineNr"> 716 </span>]
-<span id="L717" class="LineNr"> 717 </span>
-<span id="L718" class="LineNr"> 718 </span><span class="Comment"># we'll not use the recipe-editor's 'bottom' element directly, because later</span>
-<span id="L719" class="LineNr"> 719 </span><span class="Comment"># layers will add other stuff to the left side below the editor (error messages)</span>
-<span id="L720" class="LineNr"> 720 </span>
-<span id="L721" class="LineNr"> 721 </span><span class="muData">container</span> environment [
-<span id="L722" class="LineNr"> 722 </span>  recipe-bottom:num
-<span id="L723" class="LineNr"> 723 </span>]
-<span id="L724" class="LineNr"> 724 </span>
-<span id="L725" class="LineNr"> 725 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L443'>&lt;render-recipe-components-end&gt;</a></span> [
-<span id="L726" class="LineNr"> 726 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">recipe-bottom:offset</span>, row
-<span id="L727" class="LineNr"> 727 </span>]
-<span id="L728" class="LineNr"> 728 </span>
-<span id="L729" class="LineNr"> 729 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L62'>&lt;global-keypress&gt;</a></span> [
-<span id="L730" class="LineNr"> 730 </span>  <span class="Delimiter">{</span>
-<span id="L731" class="LineNr"> 731 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> sandbox-in-focus?
-<span id="L732" class="LineNr"> 732 </span>  <span class="Conceal">¦</span> down-arrow?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">65516/down-arrow</span>
-<span id="L733" class="LineNr"> 733 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> down-arrow?
-<span id="L734" class="LineNr"> 734 </span>  <span class="Conceal">¦</span> recipe-editor:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">recipes:offset</span>
-<span id="L735" class="LineNr"> 735 </span>  <span class="Conceal">¦</span> recipe-cursor-row:num <span class="Special">&lt;-</span> get *recipe-editor, <span class="Constant">cursor-row:offset</span>
-<span id="L736" class="LineNr"> 736 </span>  <span class="Conceal">¦</span> recipe-editor-bottom:num <span class="Special">&lt;-</span> get *recipe-editor, <span class="Constant">bottom:offset</span>
-<span id="L737" class="LineNr"> 737 </span>  <span class="Conceal">¦</span> at-bottom-of-editor?:bool <span class="Special">&lt;-</span> greater-or-equal recipe-cursor-row, recipe-editor-bottom
-<span id="L738" class="LineNr"> 738 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> at-bottom-of-editor?
-<span id="L739" class="LineNr"> 739 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a>:bool <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a> env, <a href='../081print.mu.html#L4'>screen</a>
-<span id="L740" class="LineNr"> 740 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a>
-<span id="L741" class="LineNr"> 741 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L742" class="LineNr"> 742 </span>  <span class="Delimiter">}</span>
+<span id="L675" class="LineNr"> 675 </span>  memory-should-contain [
+<span id="L676" class="LineNr"> 676 </span>  <span class="Conceal">¦</span> 1:array:character <span class="Special">&lt;-</span> <span class="Constant">[abdefc]</span>
+<span id="L677" class="LineNr"> 677 </span>  ]
+<span id="L678" class="LineNr"> 678 </span>]
+<span id="L679" class="LineNr"> 679 </span>
+<span id="L680" class="LineNr"> 680 </span><span class="Comment"># keep the bottom of recipes from scrolling off the screen</span>
+<span id="L681" class="LineNr"> 681 </span>
+<span id="L682" class="LineNr"> 682 </span><span class="muScenario">scenario</span> scrolling-down-past-bottom-of-recipe-editor [
+<span id="L683" class="LineNr"> 683 </span>  <span class="Constant">local-scope</span>
+<span id="L684" class="LineNr"> 684 </span>  trace-until <span class="Constant">100/app</span>
+<span id="L685" class="LineNr"> 685 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L686" class="LineNr"> 686 </span>  assume-resources [
+<span id="L687" class="LineNr"> 687 </span>  ]
+<span id="L688" class="LineNr"> 688 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L689" class="LineNr"> 689 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L690" class="LineNr"> 690 </span>  assume-console [
+<span id="L691" class="LineNr"> 691 </span>  <span class="Conceal">¦</span> press enter
+<span id="L692" class="LineNr"> 692 </span>  <span class="Conceal">¦</span> press down-arrow
+<span id="L693" class="LineNr"> 693 </span>  ]
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+<span id="L695" class="LineNr"> 695 </span>  <span class="Comment"># no scroll</span>
+<span id="L696" class="LineNr"> 696 </span>  screen-should-contain [
+<span id="L697" class="LineNr"> 697 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L698" class="LineNr"> 698 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L699" class="LineNr"> 699 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L700" class="LineNr"> 700 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L701" class="LineNr"> 701 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L702" class="LineNr"> 702 </span>  ]
+<span id="L703" class="LineNr"> 703 </span>]
+<span id="L704" class="LineNr"> 704 </span>
+<span id="L705" class="LineNr"> 705 </span><span class="muScenario">scenario</span> cursor-down-in-recipe-editor [
+<span id="L706" class="LineNr"> 706 </span>  <span class="Constant">local-scope</span>
+<span id="L707" class="LineNr"> 707 </span>  trace-until <span class="Constant">100/app</span>
+<span id="L708" class="LineNr"> 708 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L709" class="LineNr"> 709 </span>  assume-resources [
+<span id="L710" class="LineNr"> 710 </span>  ]
+<span id="L711" class="LineNr"> 711 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L712" class="LineNr"> 712 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L713" class="LineNr"> 713 </span>  assume-console [
+<span id="L714" class="LineNr"> 714 </span>  <span class="Conceal">¦</span> press enter
+<span id="L715" class="LineNr"> 715 </span>  <span class="Conceal">¦</span> press up-arrow
+<span id="L716" class="LineNr"> 716 </span>  <span class="Conceal">¦</span> press down-arrow  <span class="Comment"># while cursor isn't at bottom</span>
+<span id="L717" class="LineNr"> 717 </span>  ]
+<span id="L718" class="LineNr"> 718 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L719" class="LineNr"> 719 </span>  cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L720" class="LineNr"> 720 </span>  print <a href='../081print.mu.html#L4'>screen</a>, cursor
+<span id="L721" class="LineNr"> 721 </span>  <span class="Comment"># cursor moves back to bottom</span>
+<span id="L722" class="LineNr"> 722 </span>  screen-should-contain [
+<span id="L723" class="LineNr"> 723 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L724" class="LineNr"> 724 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L725" class="LineNr"> 725 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣                                                 ╎─────────────────────────────────────────────────.</span>
+<span id="L726" class="LineNr"> 726 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L727" class="LineNr"> 727 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L728" class="LineNr"> 728 </span>  ]
+<span id="L729" class="LineNr"> 729 </span>]
+<span id="L730" class="LineNr"> 730 </span>
+<span id="L731" class="LineNr"> 731 </span><span class="Comment"># we'll not use the recipe-editor's 'bottom' element directly, because later</span>
+<span id="L732" class="LineNr"> 732 </span><span class="Comment"># layers will add other stuff to the left side below the editor (error messages)</span>
+<span id="L733" class="LineNr"> 733 </span>
+<span id="L734" class="LineNr"> 734 </span><span class="muData">container</span> environment [
+<span id="L735" class="LineNr"> 735 </span>  recipe-bottom:num
+<span id="L736" class="LineNr"> 736 </span>]
+<span id="L737" class="LineNr"> 737 </span>
+<span id="L738" class="LineNr"> 738 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L443'>&lt;render-recipe-components-end&gt;</a></span> [
+<span id="L739" class="LineNr"> 739 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">recipe-bottom:offset</span>, row
+<span id="L740" class="LineNr"> 740 </span>]
+<span id="L741" class="LineNr"> 741 </span>
+<span id="L742" class="LineNr"> 742 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L62'>&lt;global-keypress&gt;</a></span> [
 <span id="L743" class="LineNr"> 743 </span>  <span class="Delimiter">{</span>
 <span id="L744" class="LineNr"> 744 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> sandbox-in-focus?
-<span id="L745" class="LineNr"> 745 </span>  <span class="Conceal">¦</span> page-down?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">65518/page-down</span>
-<span id="L746" class="LineNr"> 746 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> page-down?
-<span id="L747" class="LineNr"> 747 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a>:bool <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a> env, <a href='../081print.mu.html#L4'>screen</a>
-<span id="L748" class="LineNr"> 748 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a>
-<span id="L749" class="LineNr"> 749 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L750" class="LineNr"> 750 </span>  <span class="Delimiter">}</span>
-<span id="L751" class="LineNr"> 751 </span>]
-<span id="L752" class="LineNr"> 752 </span>
-<span id="L753" class="LineNr"> 753 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L67'>&lt;global-type&gt;</a></span> [
-<span id="L754" class="LineNr"> 754 </span>  <span class="Delimiter">{</span>
-<span id="L755" class="LineNr"> 755 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> sandbox-in-focus?
-<span id="L756" class="LineNr"> 756 </span>  <span class="Conceal">¦</span> page-down?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">6/ctrl-f</span>
-<span id="L757" class="LineNr"> 757 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> page-down?
-<span id="L758" class="LineNr"> 758 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a>:bool <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a> env, <a href='../081print.mu.html#L4'>screen</a>
-<span id="L759" class="LineNr"> 759 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a>
-<span id="L760" class="LineNr"> 760 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L761" class="LineNr"> 761 </span>  <span class="Delimiter">}</span>
-<span id="L762" class="LineNr"> 762 </span>]
-<span id="L763" class="LineNr"> 763 </span>
-<span id="L764" class="LineNr"> 764 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L764'>more-to-scroll?</a> env:&amp;:environment, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a><span class="muRecipe"> -&gt; </span>result:bool [
-<span id="L765" class="LineNr"> 765 </span>  <span class="Constant">local-scope</span>
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-<span id="L767" class="LineNr"> 767 </span>  recipe-bottom:num <span class="Special">&lt;-</span> get *env, <span class="Constant">recipe-bottom:offset</span>
-<span id="L768" class="LineNr"> 768 </span>  height:num <span class="Special">&lt;-</span> <a href='../081print.mu.html#L748'>screen-height</a> <a href='../081print.mu.html#L4'>screen</a>
-<span id="L769" class="LineNr"> 769 </span>  result <span class="Special">&lt;-</span> greater-or-equal recipe-bottom, height
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-<span id="L771" class="LineNr"> 771 </span>
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-<span id="L774" class="LineNr"> 774 </span>  trace-until <span class="Constant">100/app</span>
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-<span id="L776" class="LineNr"> 776 </span>  assume-resources [
-<span id="L777" class="LineNr"> 777 </span>  ]
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-<span id="L779" class="LineNr"> 779 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L780" class="LineNr"> 780 </span>  assume-console [
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-<span id="L782" class="LineNr"> 782 </span>  <span class="Conceal">¦</span> press enter
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-<span id="L784" class="LineNr"> 784 </span>  <span class="Conceal">¦</span> press up-arrow
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-<span id="L786" class="LineNr"> 786 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>  <span class="Comment"># or ctrl-f</span>
-<span id="L787" class="LineNr"> 787 </span>  ]
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-<span id="L789" class="LineNr"> 789 </span>  <span class="Comment"># no scroll, and cursor remains at top line</span>
-<span id="L790" class="LineNr"> 790 </span>  screen-should-contain [
-<span id="L791" class="LineNr"> 791 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L792" class="LineNr"> 792 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L793" class="LineNr"> 793 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L794" class="LineNr"> 794 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L795" class="LineNr"> 795 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L796" class="LineNr"> 796 </span>  ]
-<span id="L797" class="LineNr"> 797 </span>]
-<span id="L798" class="LineNr"> 798 </span>
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-<span id="L800" class="LineNr"> 800 </span>  <span class="Constant">local-scope</span>
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-<span id="L802" class="LineNr"> 802 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L803" class="LineNr"> 803 </span>  assume-resources [
-<span id="L804" class="LineNr"> 804 </span>  ]
-<span id="L805" class="LineNr"> 805 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[ab</span>
-<span id="L806" class="LineNr"> 806 </span><span class="Constant">cd]</span>
-<span id="L807" class="LineNr"> 807 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L808" class="LineNr"> 808 </span>  assume-console [
-<span id="L809" class="LineNr"> 809 </span>  <span class="Conceal">¦</span> <span class="Comment"># add a line</span>
-<span id="L810" class="LineNr"> 810 </span>  <span class="Conceal">¦</span> press enter
-<span id="L811" class="LineNr"> 811 </span>  <span class="Conceal">¦</span> <span class="Comment"># switch to sandbox</span>
-<span id="L812" class="LineNr"> 812 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L813" class="LineNr"> 813 </span>  <span class="Conceal">¦</span> <span class="Comment"># move cursor</span>
-<span id="L814" class="LineNr"> 814 </span>  <span class="Conceal">¦</span> press down-arrow
-<span id="L815" class="LineNr"> 815 </span>  ]
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-<span id="L817" class="LineNr"> 817 </span>  cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
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-<span id="L821" class="LineNr"> 821 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L822" class="LineNr"> 822 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎ab                                               .</span>
-<span id="L823" class="LineNr"> 823 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣d                                               .</span>
-<span id="L824" class="LineNr"> 824 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L825" class="LineNr"> 825 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L826" class="LineNr"> 826 </span>  ]
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-<span id="L834" class="LineNr"> 834 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L835" class="LineNr"> 835 </span>  <span class="Comment"># initialize</span>
-<span id="L836" class="LineNr"> 836 </span>  assume-resources [
-<span id="L837" class="LineNr"> 837 </span>  ]
-<span id="L838" class="LineNr"> 838 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 2, 2]</span>
-<span id="L839" class="LineNr"> 839 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L840" class="LineNr"> 840 </span>  assume-console [
-<span id="L841" class="LineNr"> 841 </span>  <span class="Conceal">¦</span> <span class="Comment"># create a sandbox</span>
-<span id="L842" class="LineNr"> 842 </span>  <span class="Conceal">¦</span> press F4
-<span id="L843" class="LineNr"> 843 </span>  ]
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-<span id="L845" class="LineNr"> 845 </span>  screen-should-contain [
-<span id="L846" class="LineNr"> 846 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L847" class="LineNr"> 847 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L848" class="LineNr"> 848 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L849" class="LineNr"> 849 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L850" class="LineNr"> 850 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L851" class="LineNr"> 851 </span>  ]
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+<span id="L746" class="LineNr"> 746 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> down-arrow?
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+<span id="L748" class="LineNr"> 748 </span>  <span class="Conceal">¦</span> recipe-cursor-row:num <span class="Special">&lt;-</span> get *recipe-editor, <span class="Constant">cursor-row:offset</span>
+<span id="L749" class="LineNr"> 749 </span>  <span class="Conceal">¦</span> recipe-editor-bottom:num <span class="Special">&lt;-</span> get *recipe-editor, <span class="Constant">bottom:offset</span>
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+<span id="L753" class="LineNr"> 753 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> <a href='005-sandbox.mu.html#L777'>more-to-scroll?</a>
+<span id="L754" class="LineNr"> 754 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L755" class="LineNr"> 755 </span>  <span class="Delimiter">}</span>
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+<span id="L761" class="LineNr"> 761 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> <a href='005-sandbox.mu.html#L777'>more-to-scroll?</a>
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+<span id="L763" class="LineNr"> 763 </span>  <span class="Delimiter">}</span>
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+<span id="L767" class="LineNr"> 767 </span>  <span class="Delimiter">{</span>
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+<span id="L769" class="LineNr"> 769 </span>  <span class="Conceal">¦</span> page-down?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">6/ctrl-f</span>
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+<span id="L771" class="LineNr"> 771 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L777'>more-to-scroll?</a>:bool <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L777'>more-to-scroll?</a> env, <a href='../081print.mu.html#L4'>screen</a>
+<span id="L772" class="LineNr"> 772 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> <a href='005-sandbox.mu.html#L777'>more-to-scroll?</a>
+<span id="L773" class="LineNr"> 773 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L774" class="LineNr"> 774 </span>  <span class="Delimiter">}</span>
+<span id="L775" class="LineNr"> 775 </span>]
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+<span id="L777" class="LineNr"> 777 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L777'>more-to-scroll?</a> env:&amp;:environment, <a href='../081print.mu.html#L4'>screen</a>:&amp;:<a href='../081print.mu.html#L4'>screen</a><span class="muRecipe"> -&gt; </span>result:bool [
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+<span id="L782" class="LineNr"> 782 </span>  result <span class="Special">&lt;-</span> greater-or-equal recipe-bottom, height
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+<span id="L785" class="LineNr"> 785 </span><span class="muScenario">scenario</span> scrolling-down-past-bottom-of-recipe-editor-2 [
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+<span id="L789" class="LineNr"> 789 </span>  assume-resources [
+<span id="L790" class="LineNr"> 790 </span>  ]
+<span id="L791" class="LineNr"> 791 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L792" class="LineNr"> 792 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L793" class="LineNr"> 793 </span>  assume-console [
+<span id="L794" class="LineNr"> 794 </span>  <span class="Conceal">¦</span> <span class="Comment"># add a line</span>
+<span id="L795" class="LineNr"> 795 </span>  <span class="Conceal">¦</span> press enter
+<span id="L796" class="LineNr"> 796 </span>  <span class="Conceal">¦</span> <span class="Comment"># cursor back to top line</span>
+<span id="L797" class="LineNr"> 797 </span>  <span class="Conceal">¦</span> press up-arrow
+<span id="L798" class="LineNr"> 798 </span>  <span class="Conceal">¦</span> <span class="Comment"># try to scroll</span>
+<span id="L799" class="LineNr"> 799 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>  <span class="Comment"># or ctrl-f</span>
+<span id="L800" class="LineNr"> 800 </span>  ]
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+<span id="L802" class="LineNr"> 802 </span>  <span class="Comment"># no scroll, and cursor remains at top line</span>
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+<span id="L804" class="LineNr"> 804 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L805" class="LineNr"> 805 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L806" class="LineNr"> 806 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L807" class="LineNr"> 807 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L808" class="LineNr"> 808 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L809" class="LineNr"> 809 </span>  ]
+<span id="L810" class="LineNr"> 810 </span>]
+<span id="L811" class="LineNr"> 811 </span>
+<span id="L812" class="LineNr"> 812 </span><span class="muScenario">scenario</span> scrolling-down-past-bottom-of-recipe-editor-3 [
+<span id="L813" class="LineNr"> 813 </span>  <span class="Constant">local-scope</span>
+<span id="L814" class="LineNr"> 814 </span>  trace-until <span class="Constant">100/app</span>
+<span id="L815" class="LineNr"> 815 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L816" class="LineNr"> 816 </span>  assume-resources [
+<span id="L817" class="LineNr"> 817 </span>  ]
+<span id="L818" class="LineNr"> 818 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[ab</span>
+<span id="L819" class="LineNr"> 819 </span><span class="Constant">cd]</span>
+<span id="L820" class="LineNr"> 820 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L821" class="LineNr"> 821 </span>  assume-console [
+<span id="L822" class="LineNr"> 822 </span>  <span class="Conceal">¦</span> <span class="Comment"># add a line</span>
+<span id="L823" class="LineNr"> 823 </span>  <span class="Conceal">¦</span> press enter
+<span id="L824" class="LineNr"> 824 </span>  <span class="Conceal">¦</span> <span class="Comment"># switch to sandbox</span>
+<span id="L825" class="LineNr"> 825 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L826" class="LineNr"> 826 </span>  <span class="Conceal">¦</span> <span class="Comment"># move cursor</span>
+<span id="L827" class="LineNr"> 827 </span>  <span class="Conceal">¦</span> press down-arrow
+<span id="L828" class="LineNr"> 828 </span>  ]
+<span id="L829" class="LineNr"> 829 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L830" class="LineNr"> 830 </span>  cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L831" class="LineNr"> 831 </span>  print <a href='../081print.mu.html#L4'>screen</a>, cursor
+<span id="L832" class="LineNr"> 832 </span>  <span class="Comment"># no scroll on recipe side, cursor moves on sandbox side</span>
+<span id="L833" class="LineNr"> 833 </span>  screen-should-contain [
+<span id="L834" class="LineNr"> 834 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L835" class="LineNr"> 835 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎ab                                               .</span>
+<span id="L836" class="LineNr"> 836 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣d                                               .</span>
+<span id="L837" class="LineNr"> 837 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L838" class="LineNr"> 838 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L839" class="LineNr"> 839 </span>  ]
+<span id="L840" class="LineNr"> 840 </span>]
+<span id="L841" class="LineNr"> 841 </span>
+<span id="L842" class="LineNr"> 842 </span><span class="Comment"># scrolling through sandboxes</span>
+<span id="L843" class="LineNr"> 843 </span>
+<span id="L844" class="LineNr"> 844 </span><span class="muScenario">scenario</span> scrolling-down-past-bottom-of-sandbox-editor [
+<span id="L845" class="LineNr"> 845 </span>  <span class="Constant">local-scope</span>
+<span id="L846" class="LineNr"> 846 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L847" class="LineNr"> 847 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L848" class="LineNr"> 848 </span>  <span class="Comment"># initialize</span>
+<span id="L849" class="LineNr"> 849 </span>  assume-resources [
+<span id="L850" class="LineNr"> 850 </span>  ]
+<span id="L851" class="LineNr"> 851 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 2, 2]</span>
+<span id="L852" class="LineNr"> 852 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
 <span id="L853" class="LineNr"> 853 </span>  assume-console [
-<span id="L854" class="LineNr"> 854 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L855" class="LineNr"> 855 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L854" class="LineNr"> 854 </span>  <span class="Conceal">¦</span> <span class="Comment"># create a sandbox</span>
+<span id="L855" class="LineNr"> 855 </span>  <span class="Conceal">¦</span> press F4
 <span id="L856" class="LineNr"> 856 </span>  ]
-<span id="L857" class="LineNr"> 857 </span>  run [
-<span id="L858" class="LineNr"> 858 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L859" class="LineNr"> 859 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L860" class="LineNr"> 860 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L861" class="LineNr"> 861 </span>  ]
-<span id="L862" class="LineNr"> 862 </span>  <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
-<span id="L863" class="LineNr"> 863 </span>  <span class="Comment"># cursor moves to first sandbox</span>
-<span id="L864" class="LineNr"> 864 </span>  screen-should-contain [
-<span id="L865" class="LineNr"> 865 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L866" class="LineNr"> 866 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L867" class="LineNr"> 867 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎␣   edit       copy       to recipe    delete    .</span>
-<span id="L868" class="LineNr"> 868 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L869" class="LineNr"> 869 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L870" class="LineNr"> 870 </span>  ]
-<span id="L871" class="LineNr"> 871 </span>  <span class="Comment"># hit 'page-up'</span>
-<span id="L872" class="LineNr"> 872 </span>  assume-console [
-<span id="L873" class="LineNr"> 873 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
+<span id="L857" class="LineNr"> 857 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L858" class="LineNr"> 858 </span>  screen-should-contain [
+<span id="L859" class="LineNr"> 859 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L860" class="LineNr"> 860 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L861" class="LineNr"> 861 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L862" class="LineNr"> 862 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L863" class="LineNr"> 863 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L864" class="LineNr"> 864 </span>  ]
+<span id="L865" class="LineNr"> 865 </span>  <span class="Comment"># switch to sandbox window and hit 'page-down'</span>
+<span id="L866" class="LineNr"> 866 </span>  assume-console [
+<span id="L867" class="LineNr"> 867 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L868" class="LineNr"> 868 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L869" class="LineNr"> 869 </span>  ]
+<span id="L870" class="LineNr"> 870 </span>  run [
+<span id="L871" class="LineNr"> 871 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L872" class="LineNr"> 872 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L873" class="LineNr"> 873 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
 <span id="L874" class="LineNr"> 874 </span>  ]
-<span id="L875" class="LineNr"> 875 </span>  run [
-<span id="L876" class="LineNr"> 876 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L877" class="LineNr"> 877 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L878" class="LineNr"> 878 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L879" class="LineNr"> 879 </span>  ]
-<span id="L880" class="LineNr"> 880 </span>  <span class="Comment"># sandbox editor displays again, cursor is in editor</span>
-<span id="L881" class="LineNr"> 881 </span>  screen-should-contain [
-<span id="L882" class="LineNr"> 882 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L883" class="LineNr"> 883 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣                                                .</span>
-<span id="L884" class="LineNr"> 884 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L885" class="LineNr"> 885 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L886" class="LineNr"> 886 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L875" class="LineNr"> 875 </span>  <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
+<span id="L876" class="LineNr"> 876 </span>  <span class="Comment"># cursor moves to first sandbox</span>
+<span id="L877" class="LineNr"> 877 </span>  screen-should-contain [
+<span id="L878" class="LineNr"> 878 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L879" class="LineNr"> 879 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L880" class="LineNr"> 880 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎␣   edit       copy       to recipe    delete    .</span>
+<span id="L881" class="LineNr"> 881 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L882" class="LineNr"> 882 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L883" class="LineNr"> 883 </span>  ]
+<span id="L884" class="LineNr"> 884 </span>  <span class="Comment"># hit 'page-up'</span>
+<span id="L885" class="LineNr"> 885 </span>  assume-console [
+<span id="L886" class="LineNr"> 886 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
 <span id="L887" class="LineNr"> 887 </span>  ]
-<span id="L888" class="LineNr"> 888 </span>]
-<span id="L889" class="LineNr"> 889 </span>
-<span id="L890" class="LineNr"> 890 </span><span class="Comment"># page-down on sandbox side updates render-from to scroll sandboxes</span>
-<span id="L891" class="LineNr"> 891 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L62'>&lt;global-keypress&gt;</a></span> [
-<span id="L892" class="LineNr"> 892 </span>  <span class="Delimiter">{</span>
-<span id="L893" class="LineNr"> 893 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-in-focus?
-<span id="L894" class="LineNr"> 894 </span>  <span class="Conceal">¦</span> page-down?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">65518/page-down</span>
-<span id="L895" class="LineNr"> 895 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> page-down?
-<span id="L896" class="LineNr"> 896 </span>  <span class="Conceal">¦</span> sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L897" class="LineNr"> 897 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox
-<span id="L898" class="LineNr"> 898 </span>  <span class="Conceal">¦</span> <span class="Comment"># slide down if possible</span>
-<span id="L899" class="LineNr"> 899 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L900" class="LineNr"> 900 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
-<span id="L901" class="LineNr"> 901 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> number-of-sandboxes:num <span class="Special">&lt;-</span> get *env, <span class="Constant">number-of-sandboxes:offset</span>
-<span id="L902" class="LineNr"> 902 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> max:num <span class="Special">&lt;-</span> subtract number-of-sandboxes,<span class="Constant"> 1</span>
-<span id="L903" class="LineNr"> 903 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> at-end?:bool <span class="Special">&lt;-</span> greater-or-equal render-from, max
-<span id="L904" class="LineNr"> 904 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop-if</span> at-end?, <span class="Constant">+next-event</span>  <span class="Comment"># render nothing</span>
-<span id="L905" class="LineNr"> 905 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> render-from <span class="Special">&lt;-</span> add render-from,<span class="Constant"> 1</span>
-<span id="L906" class="LineNr"> 906 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>, render-from
-<span id="L907" class="LineNr"> 907 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L908" class="LineNr"> 908 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L909" class="LineNr"> 909 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L910" class="LineNr"> 910 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L911" class="LineNr"> 911 </span>  <span class="Delimiter">}</span>
-<span id="L912" class="LineNr"> 912 </span>]
-<span id="L913" class="LineNr"> 913 </span>
-<span id="L914" class="LineNr"> 914 </span><span class="Comment"># update-cursor takes render-from into account</span>
-<span id="L915" class="LineNr"> 915 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L469'>&lt;update-cursor-special-cases&gt;</a></span> [
-<span id="L916" class="LineNr"> 916 </span>  <span class="Delimiter">{</span>
-<span id="L917" class="LineNr"> 917 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-in-focus?
-<span id="L918" class="LineNr"> 918 </span>  <span class="Conceal">¦</span> render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
-<span id="L919" class="LineNr"> 919 </span>  <span class="Conceal">¦</span> scrolling?:bool <span class="Special">&lt;-</span> greater-or-equal render-from,<span class="Constant"> 0</span>
-<span id="L920" class="LineNr"> 920 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> scrolling?
-<span id="L921" class="LineNr"> 921 </span>  <span class="Conceal">¦</span> cursor-column:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
-<span id="L922" class="LineNr"> 922 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">2/row</span>, cursor-column  <span class="Comment"># highlighted sandbox will always start at row 2</span>
-<span id="L923" class="LineNr"> 923 </span>  <span class="Conceal">¦</span> <span class="muControl">return</span>
+<span id="L888" class="LineNr"> 888 </span>  run [
+<span id="L889" class="LineNr"> 889 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L890" class="LineNr"> 890 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L891" class="LineNr"> 891 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
+<span id="L892" class="LineNr"> 892 </span>  ]
+<span id="L893" class="LineNr"> 893 </span>  <span class="Comment"># sandbox editor displays again, cursor is in editor</span>
+<span id="L894" class="LineNr"> 894 </span>  screen-should-contain [
+<span id="L895" class="LineNr"> 895 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L896" class="LineNr"> 896 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣                                                .</span>
+<span id="L897" class="LineNr"> 897 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L898" class="LineNr"> 898 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L899" class="LineNr"> 899 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L900" class="LineNr"> 900 </span>  ]
+<span id="L901" class="LineNr"> 901 </span>]
+<span id="L902" class="LineNr"> 902 </span>
+<span id="L903" class="LineNr"> 903 </span><span class="Comment"># page-down on sandbox side updates render-from to scroll sandboxes</span>
+<span id="L904" class="LineNr"> 904 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L62'>&lt;global-keypress&gt;</a></span> [
+<span id="L905" class="LineNr"> 905 </span>  <span class="Delimiter">{</span>
+<span id="L906" class="LineNr"> 906 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-in-focus?
+<span id="L907" class="LineNr"> 907 </span>  <span class="Conceal">¦</span> page-down?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">65518/page-down</span>
+<span id="L908" class="LineNr"> 908 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> page-down?
+<span id="L909" class="LineNr"> 909 </span>  <span class="Conceal">¦</span> sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L910" class="LineNr"> 910 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox
+<span id="L911" class="LineNr"> 911 </span>  <span class="Conceal">¦</span> <span class="Comment"># slide down if possible</span>
+<span id="L912" class="LineNr"> 912 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L913" class="LineNr"> 913 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
+<span id="L914" class="LineNr"> 914 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> number-of-sandboxes:num <span class="Special">&lt;-</span> get *env, <span class="Constant">number-of-sandboxes:offset</span>
+<span id="L915" class="LineNr"> 915 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> max:num <span class="Special">&lt;-</span> subtract number-of-sandboxes,<span class="Constant"> 1</span>
+<span id="L916" class="LineNr"> 916 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> at-end?:bool <span class="Special">&lt;-</span> greater-or-equal render-from, max
+<span id="L917" class="LineNr"> 917 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop-if</span> at-end?, <span class="Constant">+next-event</span>  <span class="Comment"># render nothing</span>
+<span id="L918" class="LineNr"> 918 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> render-from <span class="Special">&lt;-</span> add render-from,<span class="Constant"> 1</span>
+<span id="L919" class="LineNr"> 919 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>, render-from
+<span id="L920" class="LineNr"> 920 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L921" class="LineNr"> 921 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L922" class="LineNr"> 922 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L923" class="LineNr"> 923 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
 <span id="L924" class="LineNr"> 924 </span>  <span class="Delimiter">}</span>
 <span id="L925" class="LineNr"> 925 </span>]
 <span id="L926" class="LineNr"> 926 </span>
-<span id="L927" class="LineNr"> 927 </span><span class="Comment"># 'page-up' on sandbox side is like 'page-down': updates render-from when necessary</span>
-<span id="L928" class="LineNr"> 928 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L62'>&lt;global-keypress&gt;</a></span> [
+<span id="L927" class="LineNr"> 927 </span><span class="Comment"># update-cursor takes render-from into account</span>
+<span id="L928" class="LineNr"> 928 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L470'>&lt;update-cursor-special-cases&gt;</a></span> [
 <span id="L929" class="LineNr"> 929 </span>  <span class="Delimiter">{</span>
 <span id="L930" class="LineNr"> 930 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-in-focus?
-<span id="L931" class="LineNr"> 931 </span>  <span class="Conceal">¦</span> page-up?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">65519/page-up</span>
-<span id="L932" class="LineNr"> 932 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> page-up?
-<span id="L933" class="LineNr"> 933 </span>  <span class="Conceal">¦</span> render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
-<span id="L934" class="LineNr"> 934 </span>  <span class="Conceal">¦</span> at-beginning?:bool <span class="Special">&lt;-</span> equal render-from,<span class="Constant"> -1</span>
-<span id="L935" class="LineNr"> 935 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> at-beginning?
-<span id="L936" class="LineNr"> 936 </span>  <span class="Conceal">¦</span> render-from <span class="Special">&lt;-</span> subtract render-from,<span class="Constant"> 1</span>
-<span id="L937" class="LineNr"> 937 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>, render-from
-<span id="L938" class="LineNr"> 938 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L939" class="LineNr"> 939 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L940" class="LineNr"> 940 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L941" class="LineNr"> 941 </span>  <span class="Delimiter">}</span>
-<span id="L942" class="LineNr"> 942 </span>]
-<span id="L943" class="LineNr"> 943 </span>
-<span id="L944" class="LineNr"> 944 </span><span class="Comment"># sandbox belonging to 'env' whose next-sandbox is 'in'</span>
-<span id="L945" class="LineNr"> 945 </span><span class="Comment"># return 0 if there's no such sandbox, either because 'in' doesn't exist in 'env', or because it's the first sandbox</span>
-<span id="L946" class="LineNr"> 946 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L946'>previous-sandbox</a> env:&amp;:environment, in:&amp;:sandbox<span class="muRecipe"> -&gt; </span>out:&amp;:sandbox [
-<span id="L947" class="LineNr"> 947 </span>  <span class="Constant">local-scope</span>
-<span id="L948" class="LineNr"> 948 </span>  <span class="Constant">load-ingredients</span>
-<span id="L949" class="LineNr"> 949 </span>  curr:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L950" class="LineNr"> 950 </span>  <span class="muControl">return-unless</span> curr, <span class="Constant">0/nil</span>
-<span id="L951" class="LineNr"> 951 </span>  <a href='../065duplex_list.mu.html#L29'>next</a>:&amp;:sandbox <span class="Special">&lt;-</span> get *curr, <span class="Constant">next-sandbox:offset</span>
-<span id="L952" class="LineNr"> 952 </span>  <span class="Delimiter">{</span>
-<span id="L953" class="LineNr"> 953 </span>  <span class="Conceal">¦</span> <span class="muControl">return-unless</span> <a href='../065duplex_list.mu.html#L29'>next</a>, <span class="Constant">0/nil</span>
-<span id="L954" class="LineNr"> 954 </span>  <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> equal <a href='../065duplex_list.mu.html#L29'>next</a>, in
-<span id="L955" class="LineNr"> 955 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> found?
-<span id="L956" class="LineNr"> 956 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> copy <a href='../065duplex_list.mu.html#L29'>next</a>
-<span id="L957" class="LineNr"> 957 </span>  <span class="Conceal">¦</span> <a href='../065duplex_list.mu.html#L29'>next</a> <span class="Special">&lt;-</span> get *curr, <span class="Constant">next-sandbox:offset</span>
-<span id="L958" class="LineNr"> 958 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L959" class="LineNr"> 959 </span>  <span class="Delimiter">}</span>
-<span id="L960" class="LineNr"> 960 </span>  <span class="muControl">return</span> curr
-<span id="L961" class="LineNr"> 961 </span>]
-<span id="L962" class="LineNr"> 962 </span>
-<span id="L963" class="LineNr"> 963 </span><span class="muScenario">scenario</span> scrolling-down-past-bottom-on-recipe-side [
-<span id="L964" class="LineNr"> 964 </span>  <span class="Constant">local-scope</span>
-<span id="L965" class="LineNr"> 965 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L966" class="LineNr"> 966 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L967" class="LineNr"> 967 </span>  <span class="Comment"># initialize sandbox side and create a sandbox</span>
-<span id="L968" class="LineNr"> 968 </span>  assume-resources [
-<span id="L969" class="LineNr"> 969 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
-<span id="L970" class="LineNr"> 970 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">||</span>  <span class="Comment"># file containing just a newline</span>
-<span id="L971" class="LineNr"> 971 </span>  <span class="Conceal">¦</span> ]
-<span id="L972" class="LineNr"> 972 </span>  ]
-<span id="L973" class="LineNr"> 973 </span>  <span class="Comment"># create a sandbox</span>
-<span id="L974" class="LineNr"> 974 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 2, 2]</span>
-<span id="L975" class="LineNr"> 975 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L976" class="LineNr"> 976 </span>  assume-console [
-<span id="L977" class="LineNr"> 977 </span>  <span class="Conceal">¦</span> press F4
-<span id="L978" class="LineNr"> 978 </span>  ]
-<span id="L979" class="LineNr"> 979 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L980" class="LineNr"> 980 </span>  <span class="Comment"># hit 'down' in recipe editor</span>
-<span id="L981" class="LineNr"> 981 </span>  assume-console [
-<span id="L982" class="LineNr"> 982 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L983" class="LineNr"> 983 </span>  ]
-<span id="L984" class="LineNr"> 984 </span>  run [
-<span id="L985" class="LineNr"> 985 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L986" class="LineNr"> 986 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L987" class="LineNr"> 987 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L988" class="LineNr"> 988 </span>  ]
-<span id="L989" class="LineNr"> 989 </span>  <span class="Comment"># cursor doesn't move when the end is already on-screen</span>
-<span id="L990" class="LineNr"> 990 </span>  screen-should-contain [
-<span id="L991" class="LineNr"> 991 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L992" class="LineNr"> 992 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣                                                 ╎                                                 .</span>
-<span id="L993" class="LineNr"> 993 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L994" class="LineNr"> 994 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
-<span id="L995" class="LineNr"> 995 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L931" class="LineNr"> 931 </span>  <span class="Conceal">¦</span> render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
+<span id="L932" class="LineNr"> 932 </span>  <span class="Conceal">¦</span> scrolling?:bool <span class="Special">&lt;-</span> greater-or-equal render-from,<span class="Constant"> 0</span>
+<span id="L933" class="LineNr"> 933 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> scrolling?
+<span id="L934" class="LineNr"> 934 </span>  <span class="Conceal">¦</span> cursor-column:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
+<span id="L935" class="LineNr"> 935 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='../081print.mu.html#L573'>move-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">2/row</span>, cursor-column  <span class="Comment"># highlighted sandbox will always start at row 2</span>
+<span id="L936" class="LineNr"> 936 </span>  <span class="Conceal">¦</span> <span class="muControl">return</span>
+<span id="L937" class="LineNr"> 937 </span>  <span class="Delimiter">}</span>
+<span id="L938" class="LineNr"> 938 </span>]
+<span id="L939" class="LineNr"> 939 </span>
+<span id="L940" class="LineNr"> 940 </span><span class="Comment"># 'page-up' on sandbox side is like 'page-down': updates render-from when necessary</span>
+<span id="L941" class="LineNr"> 941 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L62'>&lt;global-keypress&gt;</a></span> [
+<span id="L942" class="LineNr"> 942 </span>  <span class="Delimiter">{</span>
+<span id="L943" class="LineNr"> 943 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-in-focus?
+<span id="L944" class="LineNr"> 944 </span>  <span class="Conceal">¦</span> page-up?:bool <span class="Special">&lt;-</span> equal k, <span class="Constant">65519/page-up</span>
+<span id="L945" class="LineNr"> 945 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> page-up?
+<span id="L946" class="LineNr"> 946 </span>  <span class="Conceal">¦</span> render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
+<span id="L947" class="LineNr"> 947 </span>  <span class="Conceal">¦</span> at-beginning?:bool <span class="Special">&lt;-</span> equal render-from,<span class="Constant"> -1</span>
+<span id="L948" class="LineNr"> 948 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> at-beginning?
+<span id="L949" class="LineNr"> 949 </span>  <span class="Conceal">¦</span> render-from <span class="Special">&lt;-</span> subtract render-from,<span class="Constant"> 1</span>
+<span id="L950" class="LineNr"> 950 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>, render-from
+<span id="L951" class="LineNr"> 951 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L952" class="LineNr"> 952 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L953" class="LineNr"> 953 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L954" class="LineNr"> 954 </span>  <span class="Delimiter">}</span>
+<span id="L955" class="LineNr"> 955 </span>]
+<span id="L956" class="LineNr"> 956 </span>
+<span id="L957" class="LineNr"> 957 </span><span class="Comment"># sandbox belonging to 'env' whose next-sandbox is 'in'</span>
+<span id="L958" class="LineNr"> 958 </span><span class="Comment"># return 0 if there's no such sandbox, either because 'in' doesn't exist in 'env', or because it's the first sandbox</span>
+<span id="L959" class="LineNr"> 959 </span><span class="muRecipe">def</span> <a href='005-sandbox.mu.html#L959'>previous-sandbox</a> env:&amp;:environment, in:&amp;:sandbox<span class="muRecipe"> -&gt; </span>out:&amp;:sandbox [
+<span id="L960" class="LineNr"> 960 </span>  <span class="Constant">local-scope</span>
+<span id="L961" class="LineNr"> 961 </span>  <span class="Constant">load-ingredients</span>
+<span id="L962" class="LineNr"> 962 </span>  curr:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L963" class="LineNr"> 963 </span>  <span class="muControl">return-unless</span> curr, <span class="Constant">0/nil</span>
+<span id="L964" class="LineNr"> 964 </span>  <a href='../065duplex_list.mu.html#L29'>next</a>:&amp;:sandbox <span class="Special">&lt;-</span> get *curr, <span class="Constant">next-sandbox:offset</span>
+<span id="L965" class="LineNr"> 965 </span>  <span class="Delimiter">{</span>
+<span id="L966" class="LineNr"> 966 </span>  <span class="Conceal">¦</span> <span class="muControl">return-unless</span> <a href='../065duplex_list.mu.html#L29'>next</a>, <span class="Constant">0/nil</span>
+<span id="L967" class="LineNr"> 967 </span>  <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> equal <a href='../065duplex_list.mu.html#L29'>next</a>, in
+<span id="L968" class="LineNr"> 968 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> found?
+<span id="L969" class="LineNr"> 969 </span>  <span class="Conceal">¦</span> curr <span class="Special">&lt;-</span> copy <a href='../065duplex_list.mu.html#L29'>next</a>
+<span id="L970" class="LineNr"> 970 </span>  <span class="Conceal">¦</span> <a href='../065duplex_list.mu.html#L29'>next</a> <span class="Special">&lt;-</span> get *curr, <span class="Constant">next-sandbox:offset</span>
+<span id="L971" class="LineNr"> 971 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L972" class="LineNr"> 972 </span>  <span class="Delimiter">}</span>
+<span id="L973" class="LineNr"> 973 </span>  <span class="muControl">return</span> curr
+<span id="L974" class="LineNr"> 974 </span>]
+<span id="L975" class="LineNr"> 975 </span>
+<span id="L976" class="LineNr"> 976 </span><span class="muScenario">scenario</span> scrolling-down-past-bottom-on-recipe-side [
+<span id="L977" class="LineNr"> 977 </span>  <span class="Constant">local-scope</span>
+<span id="L978" class="LineNr"> 978 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L979" class="LineNr"> 979 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L980" class="LineNr"> 980 </span>  <span class="Comment"># initialize sandbox side and create a sandbox</span>
+<span id="L981" class="LineNr"> 981 </span>  assume-resources [
+<span id="L982" class="LineNr"> 982 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L983" class="LineNr"> 983 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">||</span>  <span class="Comment"># file containing just a newline</span>
+<span id="L984" class="LineNr"> 984 </span>  <span class="Conceal">¦</span> ]
+<span id="L985" class="LineNr"> 985 </span>  ]
+<span id="L986" class="LineNr"> 986 </span>  <span class="Comment"># create a sandbox</span>
+<span id="L987" class="LineNr"> 987 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 2, 2]</span>
+<span id="L988" class="LineNr"> 988 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L989" class="LineNr"> 989 </span>  assume-console [
+<span id="L990" class="LineNr"> 990 </span>  <span class="Conceal">¦</span> press F4
+<span id="L991" class="LineNr"> 991 </span>  ]
+<span id="L992" class="LineNr"> 992 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L993" class="LineNr"> 993 </span>  <span class="Comment"># hit 'down' in recipe editor</span>
+<span id="L994" class="LineNr"> 994 </span>  assume-console [
+<span id="L995" class="LineNr"> 995 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
 <span id="L996" class="LineNr"> 996 </span>  ]
-<span id="L997" class="LineNr"> 997 </span>]
-<span id="L998" class="LineNr"> 998 </span>
-<span id="L999" class="LineNr"> 999 </span><span class="muScenario">scenario</span> scrolling-through-multiple-sandboxes [
-<span id="L1000" class="LineNr">1000 </span>  <span class="Constant">local-scope</span>
-<span id="L1001" class="LineNr">1001 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L1002" class="LineNr">1002 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L1003" class="LineNr">1003 </span>  <span class="Comment"># initialize environment</span>
-<span id="L1004" class="LineNr">1004 </span>  assume-resources [
-<span id="L1005" class="LineNr">1005 </span>  ]
-<span id="L1006" class="LineNr">1006 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L1007" class="LineNr">1007 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L1008" class="LineNr">1008 </span>  <span class="Comment"># create 2 sandboxes</span>
-<span id="L1009" class="LineNr">1009 </span>  assume-console [
-<span id="L1010" class="LineNr">1010 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L1011" class="LineNr">1011 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L1012" class="LineNr">1012 </span>  <span class="Conceal">¦</span> press F4
-<span id="L1013" class="LineNr">1013 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
-<span id="L1014" class="LineNr">1014 </span>  <span class="Conceal">¦</span> press F4
-<span id="L1015" class="LineNr">1015 </span>  ]
-<span id="L1016" class="LineNr">1016 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1017" class="LineNr">1017 </span>  cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L1018" class="LineNr">1018 </span>  print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L1019" class="LineNr">1019 </span>  screen-should-contain [
-<span id="L1020" class="LineNr">1020 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L1021" class="LineNr">1021 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣                                                .</span>
-<span id="L1022" class="LineNr">1022 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L1023" class="LineNr">1023 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L1024" class="LineNr">1024 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L1025" class="LineNr">1025 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L1026" class="LineNr">1026 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1027" class="LineNr">1027 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L1028" class="LineNr">1028 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L1029" class="LineNr">1029 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L1030" class="LineNr">1030 </span>  ]
-<span id="L1031" class="LineNr">1031 </span>  <span class="Comment"># hit 'page-down'</span>
-<span id="L1032" class="LineNr">1032 </span>  assume-console [
-<span id="L1033" class="LineNr">1033 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L1034" class="LineNr">1034 </span>  ]
-<span id="L1035" class="LineNr">1035 </span>  run [
-<span id="L1036" class="LineNr">1036 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1037" class="LineNr">1037 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L1038" class="LineNr">1038 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L1039" class="LineNr">1039 </span>  ]
-<span id="L1040" class="LineNr">1040 </span>  <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
-<span id="L1041" class="LineNr">1041 </span>  <span class="Comment"># cursor moves to first sandbox</span>
-<span id="L1042" class="LineNr">1042 </span>  screen-should-contain [
-<span id="L1043" class="LineNr">1043 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L1044" class="LineNr">1044 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1045" class="LineNr">1045 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎␣   edit       copy       to recipe    delete    .</span>
-<span id="L1046" class="LineNr">1046 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L1047" class="LineNr">1047 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L1048" class="LineNr">1048 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1049" class="LineNr">1049 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L1050" class="LineNr">1050 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L1051" class="LineNr">1051 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L997" class="LineNr"> 997 </span>  run [
+<span id="L998" class="LineNr"> 998 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L999" class="LineNr"> 999 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L1000" class="LineNr">1000 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
+<span id="L1001" class="LineNr">1001 </span>  ]
+<span id="L1002" class="LineNr">1002 </span>  <span class="Comment"># cursor doesn't move when the end is already on-screen</span>
+<span id="L1003" class="LineNr">1003 </span>  screen-should-contain [
+<span id="L1004" class="LineNr">1004 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1005" class="LineNr">1005 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣                                                 ╎                                                 .</span>
+<span id="L1006" class="LineNr">1006 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1007" class="LineNr">1007 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
+<span id="L1008" class="LineNr">1008 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L1009" class="LineNr">1009 </span>  ]
+<span id="L1010" class="LineNr">1010 </span>]
+<span id="L1011" class="LineNr">1011 </span>
+<span id="L1012" class="LineNr">1012 </span><span class="muScenario">scenario</span> scrolling-through-multiple-sandboxes [
+<span id="L1013" class="LineNr">1013 </span>  <span class="Constant">local-scope</span>
+<span id="L1014" class="LineNr">1014 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L1015" class="LineNr">1015 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L1016" class="LineNr">1016 </span>  <span class="Comment"># initialize environment</span>
+<span id="L1017" class="LineNr">1017 </span>  assume-resources [
+<span id="L1018" class="LineNr">1018 </span>  ]
+<span id="L1019" class="LineNr">1019 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L1020" class="LineNr">1020 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L1021" class="LineNr">1021 </span>  <span class="Comment"># create 2 sandboxes</span>
+<span id="L1022" class="LineNr">1022 </span>  assume-console [
+<span id="L1023" class="LineNr">1023 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L1024" class="LineNr">1024 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L1025" class="LineNr">1025 </span>  <span class="Conceal">¦</span> press F4
+<span id="L1026" class="LineNr">1026 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
+<span id="L1027" class="LineNr">1027 </span>  <span class="Conceal">¦</span> press F4
+<span id="L1028" class="LineNr">1028 </span>  ]
+<span id="L1029" class="LineNr">1029 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1030" class="LineNr">1030 </span>  cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L1031" class="LineNr">1031 </span>  print <a href='../081print.mu.html#L4'>screen</a>, cursor
+<span id="L1032" class="LineNr">1032 </span>  screen-should-contain [
+<span id="L1033" class="LineNr">1033 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1034" class="LineNr">1034 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣                                                .</span>
+<span id="L1035" class="LineNr">1035 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L1036" class="LineNr">1036 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L1037" class="LineNr">1037 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L1038" class="LineNr">1038 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L1039" class="LineNr">1039 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1040" class="LineNr">1040 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L1041" class="LineNr">1041 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L1042" class="LineNr">1042 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L1043" class="LineNr">1043 </span>  ]
+<span id="L1044" class="LineNr">1044 </span>  <span class="Comment"># hit 'page-down'</span>
+<span id="L1045" class="LineNr">1045 </span>  assume-console [
+<span id="L1046" class="LineNr">1046 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L1047" class="LineNr">1047 </span>  ]
+<span id="L1048" class="LineNr">1048 </span>  run [
+<span id="L1049" class="LineNr">1049 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1050" class="LineNr">1050 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L1051" class="LineNr">1051 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
 <span id="L1052" class="LineNr">1052 </span>  ]
-<span id="L1053" class="LineNr">1053 </span>  <span class="Comment"># hit 'page-down' again</span>
-<span id="L1054" class="LineNr">1054 </span>  assume-console [
-<span id="L1055" class="LineNr">1055 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L1056" class="LineNr">1056 </span>  ]
-<span id="L1057" class="LineNr">1057 </span>  run [
-<span id="L1058" class="LineNr">1058 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1059" class="LineNr">1059 </span>  ]
-<span id="L1060" class="LineNr">1060 </span>  <span class="Comment"># just second sandbox displayed</span>
-<span id="L1061" class="LineNr">1061 </span>  screen-should-contain [
-<span id="L1062" class="LineNr">1062 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L1063" class="LineNr">1063 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1064" class="LineNr">1064 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
-<span id="L1065" class="LineNr">1065 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L1066" class="LineNr">1066 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L1067" class="LineNr">1067 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1068" class="LineNr">1068 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1053" class="LineNr">1053 </span>  <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
+<span id="L1054" class="LineNr">1054 </span>  <span class="Comment"># cursor moves to first sandbox</span>
+<span id="L1055" class="LineNr">1055 </span>  screen-should-contain [
+<span id="L1056" class="LineNr">1056 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1057" class="LineNr">1057 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1058" class="LineNr">1058 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎␣   edit       copy       to recipe    delete    .</span>
+<span id="L1059" class="LineNr">1059 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L1060" class="LineNr">1060 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L1061" class="LineNr">1061 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1062" class="LineNr">1062 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L1063" class="LineNr">1063 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L1064" class="LineNr">1064 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L1065" class="LineNr">1065 </span>  ]
+<span id="L1066" class="LineNr">1066 </span>  <span class="Comment"># hit 'page-down' again</span>
+<span id="L1067" class="LineNr">1067 </span>  assume-console [
+<span id="L1068" class="LineNr">1068 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
 <span id="L1069" class="LineNr">1069 </span>  ]
-<span id="L1070" class="LineNr">1070 </span>  <span class="Comment"># hit 'page-down' again</span>
-<span id="L1071" class="LineNr">1071 </span>  assume-console [
-<span id="L1072" class="LineNr">1072 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L1073" class="LineNr">1073 </span>  ]
-<span id="L1074" class="LineNr">1074 </span>  run [
-<span id="L1075" class="LineNr">1075 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1076" class="LineNr">1076 </span>  ]
-<span id="L1077" class="LineNr">1077 </span>  <span class="Comment"># no change</span>
-<span id="L1078" class="LineNr">1078 </span>  screen-should-contain [
-<span id="L1079" class="LineNr">1079 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1070" class="LineNr">1070 </span>  run [
+<span id="L1071" class="LineNr">1071 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1072" class="LineNr">1072 </span>  ]
+<span id="L1073" class="LineNr">1073 </span>  <span class="Comment"># just second sandbox displayed</span>
+<span id="L1074" class="LineNr">1074 </span>  screen-should-contain [
+<span id="L1075" class="LineNr">1075 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1076" class="LineNr">1076 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1077" class="LineNr">1077 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
+<span id="L1078" class="LineNr">1078 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L1079" class="LineNr">1079 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
 <span id="L1080" class="LineNr">1080 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1081" class="LineNr">1081 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
-<span id="L1082" class="LineNr">1082 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L1083" class="LineNr">1083 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L1084" class="LineNr">1084 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1085" class="LineNr">1085 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1081" class="LineNr">1081 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1082" class="LineNr">1082 </span>  ]
+<span id="L1083" class="LineNr">1083 </span>  <span class="Comment"># hit 'page-down' again</span>
+<span id="L1084" class="LineNr">1084 </span>  assume-console [
+<span id="L1085" class="LineNr">1085 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
 <span id="L1086" class="LineNr">1086 </span>  ]
-<span id="L1087" class="LineNr">1087 </span>  <span class="Comment"># hit 'page-up'</span>
-<span id="L1088" class="LineNr">1088 </span>  assume-console [
-<span id="L1089" class="LineNr">1089 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
-<span id="L1090" class="LineNr">1090 </span>  ]
-<span id="L1091" class="LineNr">1091 </span>  run [
-<span id="L1092" class="LineNr">1092 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1093" class="LineNr">1093 </span>  ]
-<span id="L1094" class="LineNr">1094 </span>  <span class="Comment"># back to displaying both sandboxes without editor</span>
-<span id="L1095" class="LineNr">1095 </span>  screen-should-contain [
-<span id="L1096" class="LineNr">1096 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1087" class="LineNr">1087 </span>  run [
+<span id="L1088" class="LineNr">1088 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1089" class="LineNr">1089 </span>  ]
+<span id="L1090" class="LineNr">1090 </span>  <span class="Comment"># no change</span>
+<span id="L1091" class="LineNr">1091 </span>  screen-should-contain [
+<span id="L1092" class="LineNr">1092 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1093" class="LineNr">1093 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1094" class="LineNr">1094 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
+<span id="L1095" class="LineNr">1095 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L1096" class="LineNr">1096 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
 <span id="L1097" class="LineNr">1097 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1098" class="LineNr">1098 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
-<span id="L1099" class="LineNr">1099 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L1100" class="LineNr">1100 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L1101" class="LineNr">1101 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1102" class="LineNr">1102 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L1103" class="LineNr">1103 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L1104" class="LineNr">1104 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L1105" class="LineNr">1105 </span>  ]
-<span id="L1106" class="LineNr">1106 </span>  <span class="Comment"># hit 'page-up' again</span>
-<span id="L1107" class="LineNr">1107 </span>  assume-console [
-<span id="L1108" class="LineNr">1108 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
-<span id="L1109" class="LineNr">1109 </span>  ]
-<span id="L1110" class="LineNr">1110 </span>  run [
-<span id="L1111" class="LineNr">1111 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1112" class="LineNr">1112 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L1113" class="LineNr">1113 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L1114" class="LineNr">1114 </span>  ]
-<span id="L1115" class="LineNr">1115 </span>  <span class="Comment"># back to displaying both sandboxes as well as editor</span>
-<span id="L1116" class="LineNr">1116 </span>  screen-should-contain [
-<span id="L1117" class="LineNr">1117 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L1118" class="LineNr">1118 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣                                                .</span>
-<span id="L1119" class="LineNr">1119 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L1120" class="LineNr">1120 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L1121" class="LineNr">1121 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L1122" class="LineNr">1122 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L1123" class="LineNr">1123 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1124" class="LineNr">1124 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L1125" class="LineNr">1125 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L1126" class="LineNr">1126 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L1098" class="LineNr">1098 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1099" class="LineNr">1099 </span>  ]
+<span id="L1100" class="LineNr">1100 </span>  <span class="Comment"># hit 'page-up'</span>
+<span id="L1101" class="LineNr">1101 </span>  assume-console [
+<span id="L1102" class="LineNr">1102 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
+<span id="L1103" class="LineNr">1103 </span>  ]
+<span id="L1104" class="LineNr">1104 </span>  run [
+<span id="L1105" class="LineNr">1105 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1106" class="LineNr">1106 </span>  ]
+<span id="L1107" class="LineNr">1107 </span>  <span class="Comment"># back to displaying both sandboxes without editor</span>
+<span id="L1108" class="LineNr">1108 </span>  screen-should-contain [
+<span id="L1109" class="LineNr">1109 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1110" class="LineNr">1110 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1111" class="LineNr">1111 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
+<span id="L1112" class="LineNr">1112 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L1113" class="LineNr">1113 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L1114" class="LineNr">1114 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1115" class="LineNr">1115 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L1116" class="LineNr">1116 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L1117" class="LineNr">1117 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L1118" class="LineNr">1118 </span>  ]
+<span id="L1119" class="LineNr">1119 </span>  <span class="Comment"># hit 'page-up' again</span>
+<span id="L1120" class="LineNr">1120 </span>  assume-console [
+<span id="L1121" class="LineNr">1121 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
+<span id="L1122" class="LineNr">1122 </span>  ]
+<span id="L1123" class="LineNr">1123 </span>  run [
+<span id="L1124" class="LineNr">1124 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1125" class="LineNr">1125 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L1126" class="LineNr">1126 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
 <span id="L1127" class="LineNr">1127 </span>  ]
-<span id="L1128" class="LineNr">1128 </span>  <span class="Comment"># hit 'page-up' again</span>
-<span id="L1129" class="LineNr">1129 </span>  assume-console [
-<span id="L1130" class="LineNr">1130 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
-<span id="L1131" class="LineNr">1131 </span>  ]
-<span id="L1132" class="LineNr">1132 </span>  run [
-<span id="L1133" class="LineNr">1133 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1134" class="LineNr">1134 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L1135" class="LineNr">1135 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L1136" class="LineNr">1136 </span>  ]
-<span id="L1137" class="LineNr">1137 </span>  <span class="Comment"># no change</span>
-<span id="L1138" class="LineNr">1138 </span>  screen-should-contain [
-<span id="L1139" class="LineNr">1139 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L1140" class="LineNr">1140 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣                                                .</span>
-<span id="L1141" class="LineNr">1141 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L1142" class="LineNr">1142 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L1143" class="LineNr">1143 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L1144" class="LineNr">1144 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L1145" class="LineNr">1145 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1146" class="LineNr">1146 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L1147" class="LineNr">1147 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L1148" class="LineNr">1148 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L1128" class="LineNr">1128 </span>  <span class="Comment"># back to displaying both sandboxes as well as editor</span>
+<span id="L1129" class="LineNr">1129 </span>  screen-should-contain [
+<span id="L1130" class="LineNr">1130 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1131" class="LineNr">1131 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣                                                .</span>
+<span id="L1132" class="LineNr">1132 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L1133" class="LineNr">1133 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L1134" class="LineNr">1134 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L1135" class="LineNr">1135 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L1136" class="LineNr">1136 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1137" class="LineNr">1137 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L1138" class="LineNr">1138 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L1139" class="LineNr">1139 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L1140" class="LineNr">1140 </span>  ]
+<span id="L1141" class="LineNr">1141 </span>  <span class="Comment"># hit 'page-up' again</span>
+<span id="L1142" class="LineNr">1142 </span>  assume-console [
+<span id="L1143" class="LineNr">1143 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
+<span id="L1144" class="LineNr">1144 </span>  ]
+<span id="L1145" class="LineNr">1145 </span>  run [
+<span id="L1146" class="LineNr">1146 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1147" class="LineNr">1147 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L1148" class="LineNr">1148 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
 <span id="L1149" class="LineNr">1149 </span>  ]
-<span id="L1150" class="LineNr">1150 </span>]
-<span id="L1151" class="LineNr">1151 </span>
-<span id="L1152" class="LineNr">1152 </span><span class="muScenario">scenario</span> scrolling-manages-sandbox-index-correctly [
-<span id="L1153" class="LineNr">1153 </span>  <span class="Constant">local-scope</span>
-<span id="L1154" class="LineNr">1154 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L1155" class="LineNr">1155 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L1156" class="LineNr">1156 </span>  <span class="Comment"># initialize environment</span>
-<span id="L1157" class="LineNr">1157 </span>  assume-resources [
-<span id="L1158" class="LineNr">1158 </span>  ]
-<span id="L1159" class="LineNr">1159 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L1160" class="LineNr">1160 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L1161" class="LineNr">1161 </span>  <span class="Comment"># create a sandbox</span>
-<span id="L1162" class="LineNr">1162 </span>  assume-console [
-<span id="L1163" class="LineNr">1163 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L1164" class="LineNr">1164 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
-<span id="L1165" class="LineNr">1165 </span>  <span class="Conceal">¦</span> press F4
-<span id="L1166" class="LineNr">1166 </span>  ]
-<span id="L1167" class="LineNr">1167 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1168" class="LineNr">1168 </span>  screen-should-contain [
-<span id="L1169" class="LineNr">1169 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L1170" class="LineNr">1170 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L1171" class="LineNr">1171 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L1172" class="LineNr">1172 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L1173" class="LineNr">1173 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L1174" class="LineNr">1174 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L1175" class="LineNr">1175 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1176" class="LineNr">1176 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L1177" class="LineNr">1177 </span>  ]
-<span id="L1178" class="LineNr">1178 </span>  <span class="Comment"># hit 'page-down' and 'page-up' a couple of times. sandbox index should be stable</span>
-<span id="L1179" class="LineNr">1179 </span>  assume-console [
-<span id="L1180" class="LineNr">1180 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L1181" class="LineNr">1181 </span>  ]
-<span id="L1182" class="LineNr">1182 </span>  run [
-<span id="L1183" class="LineNr">1183 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1184" class="LineNr">1184 </span>  ]
-<span id="L1185" class="LineNr">1185 </span>  <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
-<span id="L1186" class="LineNr">1186 </span>  <span class="Comment"># cursor moves to first sandbox</span>
-<span id="L1187" class="LineNr">1187 </span>  screen-should-contain [
-<span id="L1188" class="LineNr">1188 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L1189" class="LineNr">1189 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1190" class="LineNr">1190 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
-<span id="L1191" class="LineNr">1191 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L1192" class="LineNr">1192 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L1193" class="LineNr">1193 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1194" class="LineNr">1194 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L1195" class="LineNr">1195 </span>  ]
-<span id="L1196" class="LineNr">1196 </span>  <span class="Comment"># hit 'page-up' again</span>
-<span id="L1197" class="LineNr">1197 </span>  assume-console [
-<span id="L1198" class="LineNr">1198 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
-<span id="L1199" class="LineNr">1199 </span>  ]
-<span id="L1200" class="LineNr">1200 </span>  run [
-<span id="L1201" class="LineNr">1201 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1202" class="LineNr">1202 </span>  ]
-<span id="L1203" class="LineNr">1203 </span>  <span class="Comment"># back to displaying both sandboxes as well as editor</span>
-<span id="L1204" class="LineNr">1204 </span>  screen-should-contain [
-<span id="L1205" class="LineNr">1205 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L1206" class="LineNr">1206 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L1207" class="LineNr">1207 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L1208" class="LineNr">1208 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L1209" class="LineNr">1209 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L1210" class="LineNr">1210 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L1211" class="LineNr">1211 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1212" class="LineNr">1212 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L1213" class="LineNr">1213 </span>  ]
-<span id="L1214" class="LineNr">1214 </span>  <span class="Comment"># hit 'page-down'</span>
-<span id="L1215" class="LineNr">1215 </span>  assume-console [
-<span id="L1216" class="LineNr">1216 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L1217" class="LineNr">1217 </span>  ]
-<span id="L1218" class="LineNr">1218 </span>  run [
-<span id="L1219" class="LineNr">1219 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L1220" class="LineNr">1220 </span>  ]
-<span id="L1221" class="LineNr">1221 </span>  <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
-<span id="L1222" class="LineNr">1222 </span>  <span class="Comment"># cursor moves to first sandbox</span>
-<span id="L1223" class="LineNr">1223 </span>  screen-should-contain [
-<span id="L1224" class="LineNr">1224 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L1225" class="LineNr">1225 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1226" class="LineNr">1226 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
-<span id="L1227" class="LineNr">1227 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L1228" class="LineNr">1228 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L1229" class="LineNr">1229 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L1230" class="LineNr">1230 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L1231" class="LineNr">1231 </span>  ]
-<span id="L1232" class="LineNr">1232 </span>]
+<span id="L1150" class="LineNr">1150 </span>  <span class="Comment"># no change</span>
+<span id="L1151" class="LineNr">1151 </span>  screen-should-contain [
+<span id="L1152" class="LineNr">1152 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1153" class="LineNr">1153 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎␣                                                .</span>
+<span id="L1154" class="LineNr">1154 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L1155" class="LineNr">1155 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L1156" class="LineNr">1156 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L1157" class="LineNr">1157 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L1158" class="LineNr">1158 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1159" class="LineNr">1159 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L1160" class="LineNr">1160 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L1161" class="LineNr">1161 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L1162" class="LineNr">1162 </span>  ]
+<span id="L1163" class="LineNr">1163 </span>]
+<span id="L1164" class="LineNr">1164 </span>
+<span id="L1165" class="LineNr">1165 </span><span class="muScenario">scenario</span> scrolling-manages-sandbox-index-correctly [
+<span id="L1166" class="LineNr">1166 </span>  <span class="Constant">local-scope</span>
+<span id="L1167" class="LineNr">1167 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L1168" class="LineNr">1168 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L1169" class="LineNr">1169 </span>  <span class="Comment"># initialize environment</span>
+<span id="L1170" class="LineNr">1170 </span>  assume-resources [
+<span id="L1171" class="LineNr">1171 </span>  ]
+<span id="L1172" class="LineNr">1172 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L1173" class="LineNr">1173 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L1174" class="LineNr">1174 </span>  <span class="Comment"># create a sandbox</span>
+<span id="L1175" class="LineNr">1175 </span>  assume-console [
+<span id="L1176" class="LineNr">1176 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L1177" class="LineNr">1177 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
+<span id="L1178" class="LineNr">1178 </span>  <span class="Conceal">¦</span> press F4
+<span id="L1179" class="LineNr">1179 </span>  ]
+<span id="L1180" class="LineNr">1180 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1181" class="LineNr">1181 </span>  screen-should-contain [
+<span id="L1182" class="LineNr">1182 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1183" class="LineNr">1183 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1184" class="LineNr">1184 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L1185" class="LineNr">1185 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L1186" class="LineNr">1186 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L1187" class="LineNr">1187 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L1188" class="LineNr">1188 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1189" class="LineNr">1189 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1190" class="LineNr">1190 </span>  ]
+<span id="L1191" class="LineNr">1191 </span>  <span class="Comment"># hit 'page-down' and 'page-up' a couple of times. sandbox index should be stable</span>
+<span id="L1192" class="LineNr">1192 </span>  assume-console [
+<span id="L1193" class="LineNr">1193 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L1194" class="LineNr">1194 </span>  ]
+<span id="L1195" class="LineNr">1195 </span>  run [
+<span id="L1196" class="LineNr">1196 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1197" class="LineNr">1197 </span>  ]
+<span id="L1198" class="LineNr">1198 </span>  <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
+<span id="L1199" class="LineNr">1199 </span>  <span class="Comment"># cursor moves to first sandbox</span>
+<span id="L1200" class="LineNr">1200 </span>  screen-should-contain [
+<span id="L1201" class="LineNr">1201 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1202" class="LineNr">1202 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1203" class="LineNr">1203 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
+<span id="L1204" class="LineNr">1204 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L1205" class="LineNr">1205 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L1206" class="LineNr">1206 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1207" class="LineNr">1207 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1208" class="LineNr">1208 </span>  ]
+<span id="L1209" class="LineNr">1209 </span>  <span class="Comment"># hit 'page-up' again</span>
+<span id="L1210" class="LineNr">1210 </span>  assume-console [
+<span id="L1211" class="LineNr">1211 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L3179'>page-up</a>
+<span id="L1212" class="LineNr">1212 </span>  ]
+<span id="L1213" class="LineNr">1213 </span>  run [
+<span id="L1214" class="LineNr">1214 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1215" class="LineNr">1215 </span>  ]
+<span id="L1216" class="LineNr">1216 </span>  <span class="Comment"># back to displaying both sandboxes as well as editor</span>
+<span id="L1217" class="LineNr">1217 </span>  screen-should-contain [
+<span id="L1218" class="LineNr">1218 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1219" class="LineNr">1219 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1220" class="LineNr">1220 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L1221" class="LineNr">1221 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L1222" class="LineNr">1222 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L1223" class="LineNr">1223 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L1224" class="LineNr">1224 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1225" class="LineNr">1225 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1226" class="LineNr">1226 </span>  ]
+<span id="L1227" class="LineNr">1227 </span>  <span class="Comment"># hit 'page-down'</span>
+<span id="L1228" class="LineNr">1228 </span>  assume-console [
+<span id="L1229" class="LineNr">1229 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L1230" class="LineNr">1230 </span>  ]
+<span id="L1231" class="LineNr">1231 </span>  run [
+<span id="L1232" class="LineNr">1232 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L1233" class="LineNr">1233 </span>  ]
+<span id="L1234" class="LineNr">1234 </span>  <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
+<span id="L1235" class="LineNr">1235 </span>  <span class="Comment"># cursor moves to first sandbox</span>
+<span id="L1236" class="LineNr">1236 </span>  screen-should-contain [
+<span id="L1237" class="LineNr">1237 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L1238" class="LineNr">1238 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1239" class="LineNr">1239 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
+<span id="L1240" class="LineNr">1240 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L1241" class="LineNr">1241 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L1242" class="LineNr">1242 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L1243" class="LineNr">1243 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L1244" class="LineNr">1244 </span>  ]
+<span id="L1245" class="LineNr">1245 </span>]
 </pre>
 </body>
 </html>
diff --git a/html/edit/006-sandbox-copy.mu.html b/html/edit/006-sandbox-copy.mu.html
index 777ade37..702c806b 100644
--- a/html/edit/006-sandbox-copy.mu.html
+++ b/html/edit/006-sandbox-copy.mu.html
@@ -71,386 +71,390 @@ if ('onhashchange' in window) {
 <span id="L9" class="LineNr">  9 </span>  assume-resources [
 <span id="L10" class="LineNr"> 10 </span>  ]
 <span id="L11" class="LineNr"> 11 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 1, 1]</span>  <span class="Comment"># contents of sandbox editor</span>
-<span id="L12" class="LineNr"> 12 </span>  <span class="Comment"># run it</span>
-<span id="L13" class="LineNr"> 13 </span>  assume-console [
-<span id="L14" class="LineNr"> 14 </span>  <span class="Conceal">¦</span> press F4
-<span id="L15" class="LineNr"> 15 </span>  ]
-<span id="L16" class="LineNr"> 16 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L17" class="LineNr"> 17 </span>  screen-should-contain [
-<span id="L18" class="LineNr"> 18 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L19" class="LineNr"> 19 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L20" class="LineNr"> 20 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L21" class="LineNr"> 21 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L22" class="LineNr"> 22 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L23" class="LineNr"> 23 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L25" class="LineNr"> 25 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L26" class="LineNr"> 26 </span>  ]
-<span id="L27" class="LineNr"> 27 </span>  <span class="Comment"># click at left edge of 'copy' button</span>
-<span id="L28" class="LineNr"> 28 </span>  assume-console [
-<span id="L29" class="LineNr"> 29 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 69</span>
-<span id="L30" class="LineNr"> 30 </span>  ]
-<span id="L31" class="LineNr"> 31 </span>  run [
-<span id="L32" class="LineNr"> 32 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L33" class="LineNr"> 33 </span>  ]
-<span id="L34" class="LineNr"> 34 </span>  <span class="Comment"># it copies into editor</span>
-<span id="L35" class="LineNr"> 35 </span>  screen-should-contain [
-<span id="L36" class="LineNr"> 36 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L37" class="LineNr"> 37 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L38" class="LineNr"> 38 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L39" class="LineNr"> 39 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L40" class="LineNr"> 40 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L41" class="LineNr"> 41 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L42" class="LineNr"> 42 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L43" class="LineNr"> 43 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L44" class="LineNr"> 44 </span>  ]
-<span id="L45" class="LineNr"> 45 </span>  <span class="Comment"># cursor should be in the right place</span>
-<span id="L46" class="LineNr"> 46 </span>  assume-console [
-<span id="L47" class="LineNr"> 47 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
-<span id="L48" class="LineNr"> 48 </span>  ]
-<span id="L49" class="LineNr"> 49 </span>  run [
-<span id="L50" class="LineNr"> 50 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L51" class="LineNr"> 51 </span>  ]
-<span id="L52" class="LineNr"> 52 </span>  screen-should-contain [
-<span id="L53" class="LineNr"> 53 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L54" class="LineNr"> 54 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0add 1, 1                                        .</span>
-<span id="L55" class="LineNr"> 55 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L56" class="LineNr"> 56 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L57" class="LineNr"> 57 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L58" class="LineNr"> 58 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L59" class="LineNr"> 59 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L60" class="LineNr"> 60 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L61" class="LineNr"> 61 </span>  ]
-<span id="L62" class="LineNr"> 62 </span>]
-<span id="L63" class="LineNr"> 63 </span>
-<span id="L64" class="LineNr"> 64 </span><span class="muScenario">scenario</span> copy-a-sandbox-to-editor-2 [
-<span id="L65" class="LineNr"> 65 </span>  <span class="Constant">local-scope</span>
-<span id="L66" class="LineNr"> 66 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L67" class="LineNr"> 67 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L68" class="LineNr"> 68 </span>  <span class="Comment"># empty recipes</span>
-<span id="L69" class="LineNr"> 69 </span>  assume-resources [
-<span id="L70" class="LineNr"> 70 </span>  ]
-<span id="L71" class="LineNr"> 71 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 1, 1]</span>  <span class="Comment"># contents of sandbox editor</span>
-<span id="L72" class="LineNr"> 72 </span>  <span class="Comment"># run it</span>
-<span id="L73" class="LineNr"> 73 </span>  assume-console [
-<span id="L74" class="LineNr"> 74 </span>  <span class="Conceal">¦</span> press F4
-<span id="L75" class="LineNr"> 75 </span>  ]
-<span id="L76" class="LineNr"> 76 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L77" class="LineNr"> 77 </span>  screen-should-contain [
-<span id="L78" class="LineNr"> 78 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L79" class="LineNr"> 79 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L80" class="LineNr"> 80 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L81" class="LineNr"> 81 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L82" class="LineNr"> 82 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L83" class="LineNr"> 83 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L84" class="LineNr"> 84 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L85" class="LineNr"> 85 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L86" class="LineNr"> 86 </span>  ]
-<span id="L87" class="LineNr"> 87 </span>  <span class="Comment"># click at right edge of 'copy' button (just before 'delete')</span>
-<span id="L88" class="LineNr"> 88 </span>  assume-console [
-<span id="L89" class="LineNr"> 89 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 76</span>
-<span id="L90" class="LineNr"> 90 </span>  ]
-<span id="L91" class="LineNr"> 91 </span>  run [
-<span id="L92" class="LineNr"> 92 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L93" class="LineNr"> 93 </span>  ]
-<span id="L94" class="LineNr"> 94 </span>  <span class="Comment"># it copies into editor</span>
-<span id="L95" class="LineNr"> 95 </span>  screen-should-contain [
-<span id="L96" class="LineNr"> 96 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L97" class="LineNr"> 97 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L98" class="LineNr"> 98 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L99" class="LineNr"> 99 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L100" class="LineNr">100 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L101" class="LineNr">101 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L102" class="LineNr">102 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L103" class="LineNr">103 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L104" class="LineNr">104 </span>  ]
-<span id="L105" class="LineNr">105 </span>  <span class="Comment"># cursor should be in the right place</span>
-<span id="L106" class="LineNr">106 </span>  assume-console [
-<span id="L107" class="LineNr">107 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
-<span id="L108" class="LineNr">108 </span>  ]
-<span id="L109" class="LineNr">109 </span>  run [
-<span id="L110" class="LineNr">110 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L111" class="LineNr">111 </span>  ]
-<span id="L112" class="LineNr">112 </span>  screen-should-contain [
-<span id="L113" class="LineNr">113 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L114" class="LineNr">114 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0add 1, 1                                        .</span>
-<span id="L115" class="LineNr">115 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L116" class="LineNr">116 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L117" class="LineNr">117 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L118" class="LineNr">118 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L119" class="LineNr">119 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L120" class="LineNr">120 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L121" class="LineNr">121 </span>  ]
-<span id="L122" class="LineNr">122 </span>]
-<span id="L123" class="LineNr">123 </span>
-<span id="L124" class="LineNr">124 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
-<span id="L125" class="LineNr">125 </span>  <span class="Comment"># support 'copy' button</span>
-<span id="L126" class="LineNr">126 </span>  <span class="Delimiter">{</span>
-<span id="L127" class="LineNr">127 </span>  <span class="Conceal">¦</span> copy?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L138'>should-attempt-copy?</a> click-row, click-column, env
-<span id="L128" class="LineNr">128 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> copy?
-<span id="L129" class="LineNr">129 </span>  <span class="Conceal">¦</span> copy?, env <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L157'>try-copy-sandbox</a> click-row, env
+<span id="L12" class="LineNr"> 12 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L13" class="LineNr"> 13 </span>  <span class="Comment"># run it</span>
+<span id="L14" class="LineNr"> 14 </span>  assume-console [
+<span id="L15" class="LineNr"> 15 </span>  <span class="Conceal">¦</span> press F4
+<span id="L16" class="LineNr"> 16 </span>  ]
+<span id="L17" class="LineNr"> 17 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L18" class="LineNr"> 18 </span>  screen-should-contain [
+<span id="L19" class="LineNr"> 19 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L20" class="LineNr"> 20 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L21" class="LineNr"> 21 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L22" class="LineNr"> 22 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L23" class="LineNr"> 23 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L25" class="LineNr"> 25 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L26" class="LineNr"> 26 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L27" class="LineNr"> 27 </span>  ]
+<span id="L28" class="LineNr"> 28 </span>  <span class="Comment"># click at left edge of 'copy' button</span>
+<span id="L29" class="LineNr"> 29 </span>  assume-console [
+<span id="L30" class="LineNr"> 30 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 69</span>
+<span id="L31" class="LineNr"> 31 </span>  ]
+<span id="L32" class="LineNr"> 32 </span>  run [
+<span id="L33" class="LineNr"> 33 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L34" class="LineNr"> 34 </span>  ]
+<span id="L35" class="LineNr"> 35 </span>  <span class="Comment"># it copies into editor</span>
+<span id="L36" class="LineNr"> 36 </span>  screen-should-contain [
+<span id="L37" class="LineNr"> 37 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L38" class="LineNr"> 38 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L39" class="LineNr"> 39 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L40" class="LineNr"> 40 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L41" class="LineNr"> 41 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L42" class="LineNr"> 42 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L43" class="LineNr"> 43 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L44" class="LineNr"> 44 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L45" class="LineNr"> 45 </span>  ]
+<span id="L46" class="LineNr"> 46 </span>  <span class="Comment"># cursor should be in the right place</span>
+<span id="L47" class="LineNr"> 47 </span>  assume-console [
+<span id="L48" class="LineNr"> 48 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
+<span id="L49" class="LineNr"> 49 </span>  ]
+<span id="L50" class="LineNr"> 50 </span>  run [
+<span id="L51" class="LineNr"> 51 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L52" class="LineNr"> 52 </span>  ]
+<span id="L53" class="LineNr"> 53 </span>  screen-should-contain [
+<span id="L54" class="LineNr"> 54 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L55" class="LineNr"> 55 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0add 1, 1                                        .</span>
+<span id="L56" class="LineNr"> 56 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L57" class="LineNr"> 57 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L58" class="LineNr"> 58 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L59" class="LineNr"> 59 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L60" class="LineNr"> 60 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L61" class="LineNr"> 61 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L62" class="LineNr"> 62 </span>  ]
+<span id="L63" class="LineNr"> 63 </span>]
+<span id="L64" class="LineNr"> 64 </span>
+<span id="L65" class="LineNr"> 65 </span><span class="muScenario">scenario</span> copy-a-sandbox-to-editor-2 [
+<span id="L66" class="LineNr"> 66 </span>  <span class="Constant">local-scope</span>
+<span id="L67" class="LineNr"> 67 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L68" class="LineNr"> 68 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L69" class="LineNr"> 69 </span>  <span class="Comment"># empty recipes</span>
+<span id="L70" class="LineNr"> 70 </span>  assume-resources [
+<span id="L71" class="LineNr"> 71 </span>  ]
+<span id="L72" class="LineNr"> 72 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 1, 1]</span>  <span class="Comment"># contents of sandbox editor</span>
+<span id="L73" class="LineNr"> 73 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L74" class="LineNr"> 74 </span>  <span class="Comment"># run it</span>
+<span id="L75" class="LineNr"> 75 </span>  assume-console [
+<span id="L76" class="LineNr"> 76 </span>  <span class="Conceal">¦</span> press F4
+<span id="L77" class="LineNr"> 77 </span>  ]
+<span id="L78" class="LineNr"> 78 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L79" class="LineNr"> 79 </span>  screen-should-contain [
+<span id="L80" class="LineNr"> 80 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L81" class="LineNr"> 81 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L82" class="LineNr"> 82 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L83" class="LineNr"> 83 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L84" class="LineNr"> 84 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L85" class="LineNr"> 85 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L86" class="LineNr"> 86 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L87" class="LineNr"> 87 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L88" class="LineNr"> 88 </span>  ]
+<span id="L89" class="LineNr"> 89 </span>  <span class="Comment"># click at right edge of 'copy' button (just before 'delete')</span>
+<span id="L90" class="LineNr"> 90 </span>  assume-console [
+<span id="L91" class="LineNr"> 91 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 76</span>
+<span id="L92" class="LineNr"> 92 </span>  ]
+<span id="L93" class="LineNr"> 93 </span>  run [
+<span id="L94" class="LineNr"> 94 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L95" class="LineNr"> 95 </span>  ]
+<span id="L96" class="LineNr"> 96 </span>  <span class="Comment"># it copies into editor</span>
+<span id="L97" class="LineNr"> 97 </span>  screen-should-contain [
+<span id="L98" class="LineNr"> 98 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L99" class="LineNr"> 99 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L100" class="LineNr">100 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L101" class="LineNr">101 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L102" class="LineNr">102 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L103" class="LineNr">103 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L104" class="LineNr">104 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L105" class="LineNr">105 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L106" class="LineNr">106 </span>  ]
+<span id="L107" class="LineNr">107 </span>  <span class="Comment"># cursor should be in the right place</span>
+<span id="L108" class="LineNr">108 </span>  assume-console [
+<span id="L109" class="LineNr">109 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
+<span id="L110" class="LineNr">110 </span>  ]
+<span id="L111" class="LineNr">111 </span>  run [
+<span id="L112" class="LineNr">112 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L113" class="LineNr">113 </span>  ]
+<span id="L114" class="LineNr">114 </span>  screen-should-contain [
+<span id="L115" class="LineNr">115 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L116" class="LineNr">116 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0add 1, 1                                        .</span>
+<span id="L117" class="LineNr">117 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L118" class="LineNr">118 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L119" class="LineNr">119 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L120" class="LineNr">120 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L121" class="LineNr">121 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L122" class="LineNr">122 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L123" class="LineNr">123 </span>  ]
+<span id="L124" class="LineNr">124 </span>]
+<span id="L125" class="LineNr">125 </span>
+<span id="L126" class="LineNr">126 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
+<span id="L127" class="LineNr">127 </span>  <span class="Comment"># support 'copy' button</span>
+<span id="L128" class="LineNr">128 </span>  <span class="Delimiter">{</span>
+<span id="L129" class="LineNr">129 </span>  <span class="Conceal">¦</span> copy?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L140'>should-attempt-copy?</a> click-row, click-column, env
 <span id="L130" class="LineNr">130 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> copy?
-<span id="L131" class="LineNr">131 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L132" class="LineNr">132 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L133" class="LineNr">133 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L134" class="LineNr">134 </span>  <span class="Delimiter">}</span>
-<span id="L135" class="LineNr">135 </span>]
-<span id="L136" class="LineNr">136 </span>
-<span id="L137" class="LineNr">137 </span><span class="Comment"># some preconditions for attempting to copy a sandbox</span>
-<span id="L138" class="LineNr">138 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L138'>should-attempt-copy?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
-<span id="L139" class="LineNr">139 </span>  <span class="Constant">local-scope</span>
-<span id="L140" class="LineNr">140 </span>  <span class="Constant">load-ingredients</span>
-<span id="L141" class="LineNr">141 </span>  <span class="Comment"># are we below the sandbox editor?</span>
-<span id="L142" class="LineNr">142 </span>  click-sandbox-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L188'>click-on-sandbox-area?</a> click-row, click-column, env
-<span id="L143" class="LineNr">143 </span>  <span class="muControl">return-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
-<span id="L144" class="LineNr">144 </span>  <span class="Comment"># narrower, is the click in the columns spanning the 'copy' button?</span>
-<span id="L145" class="LineNr">145 </span>  first-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L146" class="LineNr">146 </span>  assert first-sandbox, <span class="Constant">[!!]</span>
-<span id="L147" class="LineNr">147 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">left:offset</span>
-<span id="L148" class="LineNr">148 </span>  sandbox-right-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">right:offset</span>
-<span id="L149" class="LineNr">149 </span>  _, _, copy-button-left:num, copy-button-right:num <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L340'>sandbox-menu-columns</a> sandbox-left-margin, sandbox-right-margin
-<span id="L150" class="LineNr">150 </span>  copy-button-vertical-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L209'>within-range?</a> click-column, copy-button-left, copy-button-right
-<span id="L151" class="LineNr">151 </span>  <span class="muControl">return-unless</span> copy-button-vertical-area?, <span class="Constant">0/false</span>
-<span id="L152" class="LineNr">152 </span>  <span class="Comment"># finally, is sandbox editor empty?</span>
-<span id="L153" class="LineNr">153 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L154" class="LineNr">154 </span>  result <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L201'>empty-editor?</a> current-sandbox
-<span id="L155" class="LineNr">155 </span>]
-<span id="L156" class="LineNr">156 </span>
-<span id="L157" class="LineNr">157 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L157'>try-copy-sandbox</a> click-row:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>clicked-on-copy-button?:bool, env:&amp;:environment [
-<span id="L158" class="LineNr">158 </span>  <span class="Constant">local-scope</span>
-<span id="L159" class="LineNr">159 </span>  <span class="Constant">load-ingredients</span>
-<span id="L160" class="LineNr">160 </span>  <span class="Comment"># identify the sandbox to copy, if the click was actually on the 'copy' button</span>
-<span id="L161" class="LineNr">161 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L173'>find-sandbox</a> env, click-row
-<span id="L162" class="LineNr">162 </span>  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
-<span id="L163" class="LineNr">163 </span>  clicked-on-copy-button? <span class="Special">&lt;-</span> copy <span class="Constant">1/true</span>
-<span id="L164" class="LineNr">164 </span>  text:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
-<span id="L165" class="LineNr">165 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L166" class="LineNr">166 </span>  current-sandbox <span class="Special">&lt;-</span> <a href='001-editor.mu.html#L72'>insert-text</a> current-sandbox, text
-<span id="L167" class="LineNr">167 </span>  <span class="Comment"># reset scroll</span>
-<span id="L168" class="LineNr">168 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>,<span class="Constant"> -1</span>
-<span id="L169" class="LineNr">169 </span>  <span class="Comment"># position cursor in sandbox editor</span>
-<span id="L170" class="LineNr">170 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox-in-focus?:offset</span>, <span class="Constant">1/true</span>
-<span id="L171" class="LineNr">171 </span>]
-<span id="L172" class="LineNr">172 </span>
-<span id="L173" class="LineNr">173 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L173'>find-sandbox</a> env:&amp;:environment, click-row:num<span class="muRecipe"> -&gt; </span>result:&amp;:sandbox [
-<span id="L174" class="LineNr">174 </span>  <span class="Constant">local-scope</span>
-<span id="L175" class="LineNr">175 </span>  <span class="Constant">load-ingredients</span>
-<span id="L176" class="LineNr">176 </span>  curr-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L177" class="LineNr">177 </span>  <span class="Delimiter">{</span>
-<span id="L178" class="LineNr">178 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> curr-sandbox
-<span id="L179" class="LineNr">179 </span>  <span class="Conceal">¦</span> start:num <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-<span id="L180" class="LineNr">180 </span>  <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> equal click-row, start
-<span id="L181" class="LineNr">181 </span>  <span class="Conceal">¦</span> <span class="muControl">return-if</span> found?, curr-sandbox
-<span id="L182" class="LineNr">182 </span>  <span class="Conceal">¦</span> curr-sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
-<span id="L183" class="LineNr">183 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L184" class="LineNr">184 </span>  <span class="Delimiter">}</span>
-<span id="L185" class="LineNr">185 </span>  <span class="muControl">return</span> <span class="Constant">0/not-found</span>
-<span id="L186" class="LineNr">186 </span>]
-<span id="L187" class="LineNr">187 </span>
-<span id="L188" class="LineNr">188 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L188'>click-on-sandbox-area?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
-<span id="L189" class="LineNr">189 </span>  <span class="Constant">local-scope</span>
-<span id="L190" class="LineNr">190 </span>  <span class="Constant">load-ingredients</span>
-<span id="L191" class="LineNr">191 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L192" class="LineNr">192 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
-<span id="L193" class="LineNr">193 </span>  on-sandbox-side?:bool <span class="Special">&lt;-</span> greater-or-equal click-column, sandbox-left-margin
-<span id="L194" class="LineNr">194 </span>  <span class="muControl">return-unless</span> on-sandbox-side?, <span class="Constant">0/false</span>
-<span id="L195" class="LineNr">195 </span>  first-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L196" class="LineNr">196 </span>  <span class="muControl">return-unless</span> first-sandbox, <span class="Constant">0/false</span>
-<span id="L197" class="LineNr">197 </span>  first-sandbox-begins:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-<span id="L198" class="LineNr">198 </span>  result <span class="Special">&lt;-</span> greater-or-equal click-row, first-sandbox-begins
-<span id="L199" class="LineNr">199 </span>]
-<span id="L200" class="LineNr">200 </span>
-<span id="L201" class="LineNr">201 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L201'>empty-editor?</a> editor:&amp;:editor<span class="muRecipe"> -&gt; </span>result:bool [
-<span id="L202" class="LineNr">202 </span>  <span class="Constant">local-scope</span>
-<span id="L203" class="LineNr">203 </span>  <span class="Constant">load-ingredients</span>
-<span id="L204" class="LineNr">204 </span>  head:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> get *editor, <span class="Constant">data:offset</span>
-<span id="L205" class="LineNr">205 </span>  first:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> <a href='../065duplex_list.mu.html#L29'>next</a> head
-<span id="L206" class="LineNr">206 </span>  result <span class="Special">&lt;-</span> not first
-<span id="L207" class="LineNr">207 </span>]
-<span id="L208" class="LineNr">208 </span>
-<span id="L209" class="LineNr">209 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L209'>within-range?</a> x:num, low:num, high:num<span class="muRecipe"> -&gt; </span>result:bool [
-<span id="L210" class="LineNr">210 </span>  <span class="Constant">local-scope</span>
-<span id="L211" class="LineNr">211 </span>  <span class="Constant">load-ingredients</span>
-<span id="L212" class="LineNr">212 </span>  not-too-far-left?:bool <span class="Special">&lt;-</span> greater-or-equal x, low
-<span id="L213" class="LineNr">213 </span>  not-too-far-right?:bool <span class="Special">&lt;-</span> lesser-or-equal x, high
-<span id="L214" class="LineNr">214 </span>  result <span class="Special">&lt;-</span> and not-too-far-left? not-too-far-right?
-<span id="L215" class="LineNr">215 </span>]
-<span id="L216" class="LineNr">216 </span>
-<span id="L217" class="LineNr">217 </span><span class="muScenario">scenario</span> copy-fails-if-sandbox-editor-not-empty [
-<span id="L218" class="LineNr">218 </span>  <span class="Constant">local-scope</span>
-<span id="L219" class="LineNr">219 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L220" class="LineNr">220 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L221" class="LineNr">221 </span>  <span class="Comment"># empty recipes</span>
-<span id="L222" class="LineNr">222 </span>  assume-resources [
-<span id="L223" class="LineNr">223 </span>  ]
-<span id="L224" class="LineNr">224 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 1, 1]</span>  <span class="Comment"># contents of sandbox editor</span>
-<span id="L225" class="LineNr">225 </span>  <span class="Comment"># run it</span>
-<span id="L226" class="LineNr">226 </span>  assume-console [
-<span id="L227" class="LineNr">227 </span>  <span class="Conceal">¦</span> press F4
-<span id="L228" class="LineNr">228 </span>  ]
-<span id="L229" class="LineNr">229 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L230" class="LineNr">230 </span>  screen-should-contain [
-<span id="L231" class="LineNr">231 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L232" class="LineNr">232 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L233" class="LineNr">233 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L234" class="LineNr">234 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L235" class="LineNr">235 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L236" class="LineNr">236 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L237" class="LineNr">237 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L238" class="LineNr">238 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L239" class="LineNr">239 </span>  ]
-<span id="L240" class="LineNr">240 </span>  <span class="Comment"># type something into the sandbox editor, then click on the 'copy' button</span>
-<span id="L241" class="LineNr">241 </span>  assume-console [
-<span id="L242" class="LineNr">242 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 70</span>  <span class="Comment"># put cursor in sandbox editor</span>
-<span id="L243" class="LineNr">243 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>  <span class="Comment"># type something</span>
-<span id="L244" class="LineNr">244 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 70</span>  <span class="Comment"># click 'copy' button</span>
-<span id="L245" class="LineNr">245 </span>  ]
-<span id="L246" class="LineNr">246 </span>  run [
-<span id="L247" class="LineNr">247 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L131" class="LineNr">131 </span>  <span class="Conceal">¦</span> copy?, env <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L159'>try-copy-sandbox</a> click-row, env
+<span id="L132" class="LineNr">132 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> copy?
+<span id="L133" class="LineNr">133 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L134" class="LineNr">134 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L135" class="LineNr">135 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L136" class="LineNr">136 </span>  <span class="Delimiter">}</span>
+<span id="L137" class="LineNr">137 </span>]
+<span id="L138" class="LineNr">138 </span>
+<span id="L139" class="LineNr">139 </span><span class="Comment"># some preconditions for attempting to copy a sandbox</span>
+<span id="L140" class="LineNr">140 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L140'>should-attempt-copy?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
+<span id="L141" class="LineNr">141 </span>  <span class="Constant">local-scope</span>
+<span id="L142" class="LineNr">142 </span>  <span class="Constant">load-ingredients</span>
+<span id="L143" class="LineNr">143 </span>  <span class="Comment"># are we below the sandbox editor?</span>
+<span id="L144" class="LineNr">144 </span>  click-sandbox-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L190'>click-on-sandbox-area?</a> click-row, click-column, env
+<span id="L145" class="LineNr">145 </span>  <span class="muControl">return-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
+<span id="L146" class="LineNr">146 </span>  <span class="Comment"># narrower, is the click in the columns spanning the 'copy' button?</span>
+<span id="L147" class="LineNr">147 </span>  first-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L148" class="LineNr">148 </span>  assert first-sandbox, <span class="Constant">[!!]</span>
+<span id="L149" class="LineNr">149 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">left:offset</span>
+<span id="L150" class="LineNr">150 </span>  sandbox-right-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">right:offset</span>
+<span id="L151" class="LineNr">151 </span>  _, _, copy-button-left:num, copy-button-right:num <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L346'>sandbox-menu-columns</a> sandbox-left-margin, sandbox-right-margin
+<span id="L152" class="LineNr">152 </span>  copy-button-vertical-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L211'>within-range?</a> click-column, copy-button-left, copy-button-right
+<span id="L153" class="LineNr">153 </span>  <span class="muControl">return-unless</span> copy-button-vertical-area?, <span class="Constant">0/false</span>
+<span id="L154" class="LineNr">154 </span>  <span class="Comment"># finally, is sandbox editor empty?</span>
+<span id="L155" class="LineNr">155 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L156" class="LineNr">156 </span>  result <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L203'>empty-editor?</a> current-sandbox
+<span id="L157" class="LineNr">157 </span>]
+<span id="L158" class="LineNr">158 </span>
+<span id="L159" class="LineNr">159 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L159'>try-copy-sandbox</a> click-row:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>clicked-on-copy-button?:bool, env:&amp;:environment [
+<span id="L160" class="LineNr">160 </span>  <span class="Constant">local-scope</span>
+<span id="L161" class="LineNr">161 </span>  <span class="Constant">load-ingredients</span>
+<span id="L162" class="LineNr">162 </span>  <span class="Comment"># identify the sandbox to copy, if the click was actually on the 'copy' button</span>
+<span id="L163" class="LineNr">163 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L175'>find-sandbox</a> env, click-row
+<span id="L164" class="LineNr">164 </span>  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
+<span id="L165" class="LineNr">165 </span>  clicked-on-copy-button? <span class="Special">&lt;-</span> copy <span class="Constant">1/true</span>
+<span id="L166" class="LineNr">166 </span>  text:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
+<span id="L167" class="LineNr">167 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L168" class="LineNr">168 </span>  current-sandbox <span class="Special">&lt;-</span> <a href='001-editor.mu.html#L72'>insert-text</a> current-sandbox, text
+<span id="L169" class="LineNr">169 </span>  <span class="Comment"># reset scroll</span>
+<span id="L170" class="LineNr">170 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>,<span class="Constant"> -1</span>
+<span id="L171" class="LineNr">171 </span>  <span class="Comment"># position cursor in sandbox editor</span>
+<span id="L172" class="LineNr">172 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox-in-focus?:offset</span>, <span class="Constant">1/true</span>
+<span id="L173" class="LineNr">173 </span>]
+<span id="L174" class="LineNr">174 </span>
+<span id="L175" class="LineNr">175 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L175'>find-sandbox</a> env:&amp;:environment, click-row:num<span class="muRecipe"> -&gt; </span>result:&amp;:sandbox [
+<span id="L176" class="LineNr">176 </span>  <span class="Constant">local-scope</span>
+<span id="L177" class="LineNr">177 </span>  <span class="Constant">load-ingredients</span>
+<span id="L178" class="LineNr">178 </span>  curr-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L179" class="LineNr">179 </span>  <span class="Delimiter">{</span>
+<span id="L180" class="LineNr">180 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> curr-sandbox
+<span id="L181" class="LineNr">181 </span>  <span class="Conceal">¦</span> start:num <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+<span id="L182" class="LineNr">182 </span>  <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> equal click-row, start
+<span id="L183" class="LineNr">183 </span>  <span class="Conceal">¦</span> <span class="muControl">return-if</span> found?, curr-sandbox
+<span id="L184" class="LineNr">184 </span>  <span class="Conceal">¦</span> curr-sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
+<span id="L185" class="LineNr">185 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L186" class="LineNr">186 </span>  <span class="Delimiter">}</span>
+<span id="L187" class="LineNr">187 </span>  <span class="muControl">return</span> <span class="Constant">0/not-found</span>
+<span id="L188" class="LineNr">188 </span>]
+<span id="L189" class="LineNr">189 </span>
+<span id="L190" class="LineNr">190 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L190'>click-on-sandbox-area?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
+<span id="L191" class="LineNr">191 </span>  <span class="Constant">local-scope</span>
+<span id="L192" class="LineNr">192 </span>  <span class="Constant">load-ingredients</span>
+<span id="L193" class="LineNr">193 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L194" class="LineNr">194 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
+<span id="L195" class="LineNr">195 </span>  on-sandbox-side?:bool <span class="Special">&lt;-</span> greater-or-equal click-column, sandbox-left-margin
+<span id="L196" class="LineNr">196 </span>  <span class="muControl">return-unless</span> on-sandbox-side?, <span class="Constant">0/false</span>
+<span id="L197" class="LineNr">197 </span>  first-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L198" class="LineNr">198 </span>  <span class="muControl">return-unless</span> first-sandbox, <span class="Constant">0/false</span>
+<span id="L199" class="LineNr">199 </span>  first-sandbox-begins:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+<span id="L200" class="LineNr">200 </span>  result <span class="Special">&lt;-</span> greater-or-equal click-row, first-sandbox-begins
+<span id="L201" class="LineNr">201 </span>]
+<span id="L202" class="LineNr">202 </span>
+<span id="L203" class="LineNr">203 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L203'>empty-editor?</a> editor:&amp;:editor<span class="muRecipe"> -&gt; </span>result:bool [
+<span id="L204" class="LineNr">204 </span>  <span class="Constant">local-scope</span>
+<span id="L205" class="LineNr">205 </span>  <span class="Constant">load-ingredients</span>
+<span id="L206" class="LineNr">206 </span>  head:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> get *editor, <span class="Constant">data:offset</span>
+<span id="L207" class="LineNr">207 </span>  first:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> <a href='../065duplex_list.mu.html#L29'>next</a> head
+<span id="L208" class="LineNr">208 </span>  result <span class="Special">&lt;-</span> not first
+<span id="L209" class="LineNr">209 </span>]
+<span id="L210" class="LineNr">210 </span>
+<span id="L211" class="LineNr">211 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L211'>within-range?</a> x:num, low:num, high:num<span class="muRecipe"> -&gt; </span>result:bool [
+<span id="L212" class="LineNr">212 </span>  <span class="Constant">local-scope</span>
+<span id="L213" class="LineNr">213 </span>  <span class="Constant">load-ingredients</span>
+<span id="L214" class="LineNr">214 </span>  not-too-far-left?:bool <span class="Special">&lt;-</span> greater-or-equal x, low
+<span id="L215" class="LineNr">215 </span>  not-too-far-right?:bool <span class="Special">&lt;-</span> lesser-or-equal x, high
+<span id="L216" class="LineNr">216 </span>  result <span class="Special">&lt;-</span> and not-too-far-left? not-too-far-right?
+<span id="L217" class="LineNr">217 </span>]
+<span id="L218" class="LineNr">218 </span>
+<span id="L219" class="LineNr">219 </span><span class="muScenario">scenario</span> copy-fails-if-sandbox-editor-not-empty [
+<span id="L220" class="LineNr">220 </span>  <span class="Constant">local-scope</span>
+<span id="L221" class="LineNr">221 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L222" class="LineNr">222 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L223" class="LineNr">223 </span>  <span class="Comment"># empty recipes</span>
+<span id="L224" class="LineNr">224 </span>  assume-resources [
+<span id="L225" class="LineNr">225 </span>  ]
+<span id="L226" class="LineNr">226 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 1, 1]</span>  <span class="Comment"># contents of sandbox editor</span>
+<span id="L227" class="LineNr">227 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L228" class="LineNr">228 </span>  <span class="Comment"># run it</span>
+<span id="L229" class="LineNr">229 </span>  assume-console [
+<span id="L230" class="LineNr">230 </span>  <span class="Conceal">¦</span> press F4
+<span id="L231" class="LineNr">231 </span>  ]
+<span id="L232" class="LineNr">232 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L233" class="LineNr">233 </span>  screen-should-contain [
+<span id="L234" class="LineNr">234 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L235" class="LineNr">235 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L236" class="LineNr">236 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L237" class="LineNr">237 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L238" class="LineNr">238 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L239" class="LineNr">239 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L240" class="LineNr">240 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L241" class="LineNr">241 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L242" class="LineNr">242 </span>  ]
+<span id="L243" class="LineNr">243 </span>  <span class="Comment"># type something into the sandbox editor, then click on the 'copy' button</span>
+<span id="L244" class="LineNr">244 </span>  assume-console [
+<span id="L245" class="LineNr">245 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 70</span>  <span class="Comment"># put cursor in sandbox editor</span>
+<span id="L246" class="LineNr">246 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>  <span class="Comment"># type something</span>
+<span id="L247" class="LineNr">247 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 70</span>  <span class="Comment"># click 'copy' button</span>
 <span id="L248" class="LineNr">248 </span>  ]
-<span id="L249" class="LineNr">249 </span>  <span class="Comment"># copy doesn't happen</span>
-<span id="L250" class="LineNr">250 </span>  screen-should-contain [
-<span id="L251" class="LineNr">251 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L252" class="LineNr">252 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0                                                .</span>
-<span id="L253" class="LineNr">253 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L254" class="LineNr">254 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L255" class="LineNr">255 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L256" class="LineNr">256 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L257" class="LineNr">257 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L258" class="LineNr">258 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L259" class="LineNr">259 </span>  ]
-<span id="L260" class="LineNr">260 </span>  <span class="Comment"># cursor should be in the right place</span>
-<span id="L261" class="LineNr">261 </span>  assume-console [
-<span id="L262" class="LineNr">262 </span>  <span class="Conceal">¦</span> type <span class="Constant">[1]</span>
-<span id="L263" class="LineNr">263 </span>  ]
-<span id="L264" class="LineNr">264 </span>  run [
-<span id="L265" class="LineNr">265 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L249" class="LineNr">249 </span>  run [
+<span id="L250" class="LineNr">250 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L251" class="LineNr">251 </span>  ]
+<span id="L252" class="LineNr">252 </span>  <span class="Comment"># copy doesn't happen</span>
+<span id="L253" class="LineNr">253 </span>  screen-should-contain [
+<span id="L254" class="LineNr">254 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L255" class="LineNr">255 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0                                                .</span>
+<span id="L256" class="LineNr">256 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L257" class="LineNr">257 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L258" class="LineNr">258 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L259" class="LineNr">259 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L260" class="LineNr">260 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L261" class="LineNr">261 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L262" class="LineNr">262 </span>  ]
+<span id="L263" class="LineNr">263 </span>  <span class="Comment"># cursor should be in the right place</span>
+<span id="L264" class="LineNr">264 </span>  assume-console [
+<span id="L265" class="LineNr">265 </span>  <span class="Conceal">¦</span> type <span class="Constant">[1]</span>
 <span id="L266" class="LineNr">266 </span>  ]
-<span id="L267" class="LineNr">267 </span>  screen-should-contain [
-<span id="L268" class="LineNr">268 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L269" class="LineNr">269 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎01                                               .</span>
-<span id="L270" class="LineNr">270 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L271" class="LineNr">271 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L272" class="LineNr">272 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L273" class="LineNr">273 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L274" class="LineNr">274 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L275" class="LineNr">275 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L276" class="LineNr">276 </span>  ]
-<span id="L277" class="LineNr">277 </span>]
-<span id="L278" class="LineNr">278 </span>
-<span id="L279" class="LineNr">279 </span><span class="SalientComment">## the 'to recipe' button makes it easy to create a function out of a sandbox</span>
-<span id="L280" class="LineNr">280 </span>
-<span id="L281" class="LineNr">281 </span><span class="muScenario">scenario</span> copy-a-sandbox-to-recipe-side [
-<span id="L282" class="LineNr">282 </span>  <span class="Constant">local-scope</span>
-<span id="L283" class="LineNr">283 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L284" class="LineNr">284 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L285" class="LineNr">285 </span>  <span class="Comment"># empty recipes</span>
-<span id="L286" class="LineNr">286 </span>  assume-resources [
-<span id="L287" class="LineNr">287 </span>  ]
-<span id="L288" class="LineNr">288 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 1, 1]</span>  <span class="Comment"># contents of sandbox editor</span>
-<span id="L289" class="LineNr">289 </span>  <span class="Comment"># run it</span>
-<span id="L290" class="LineNr">290 </span>  assume-console [
-<span id="L291" class="LineNr">291 </span>  <span class="Conceal">¦</span> press F4
-<span id="L292" class="LineNr">292 </span>  ]
-<span id="L293" class="LineNr">293 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L294" class="LineNr">294 </span>  screen-should-contain [
-<span id="L295" class="LineNr">295 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L296" class="LineNr">296 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L297" class="LineNr">297 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L298" class="LineNr">298 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L299" class="LineNr">299 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L300" class="LineNr">300 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L301" class="LineNr">301 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L302" class="LineNr">302 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L303" class="LineNr">303 </span>  ]
-<span id="L304" class="LineNr">304 </span>  <span class="Comment"># click at left edge of 'copy' button</span>
-<span id="L305" class="LineNr">305 </span>  assume-console [
-<span id="L306" class="LineNr">306 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 78</span>
+<span id="L267" class="LineNr">267 </span>  run [
+<span id="L268" class="LineNr">268 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L269" class="LineNr">269 </span>  ]
+<span id="L270" class="LineNr">270 </span>  screen-should-contain [
+<span id="L271" class="LineNr">271 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L272" class="LineNr">272 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎01                                               .</span>
+<span id="L273" class="LineNr">273 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L274" class="LineNr">274 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L275" class="LineNr">275 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L276" class="LineNr">276 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L277" class="LineNr">277 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L278" class="LineNr">278 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L279" class="LineNr">279 </span>  ]
+<span id="L280" class="LineNr">280 </span>]
+<span id="L281" class="LineNr">281 </span>
+<span id="L282" class="LineNr">282 </span><span class="SalientComment">## the 'to recipe' button makes it easy to create a function out of a sandbox</span>
+<span id="L283" class="LineNr">283 </span>
+<span id="L284" class="LineNr">284 </span><span class="muScenario">scenario</span> copy-a-sandbox-to-recipe-side [
+<span id="L285" class="LineNr">285 </span>  <span class="Constant">local-scope</span>
+<span id="L286" class="LineNr">286 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L287" class="LineNr">287 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L288" class="LineNr">288 </span>  <span class="Comment"># empty recipes</span>
+<span id="L289" class="LineNr">289 </span>  assume-resources [
+<span id="L290" class="LineNr">290 </span>  ]
+<span id="L291" class="LineNr">291 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 1, 1]</span>  <span class="Comment"># contents of sandbox editor</span>
+<span id="L292" class="LineNr">292 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L293" class="LineNr">293 </span>  <span class="Comment"># run it</span>
+<span id="L294" class="LineNr">294 </span>  assume-console [
+<span id="L295" class="LineNr">295 </span>  <span class="Conceal">¦</span> press F4
+<span id="L296" class="LineNr">296 </span>  ]
+<span id="L297" class="LineNr">297 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L298" class="LineNr">298 </span>  screen-should-contain [
+<span id="L299" class="LineNr">299 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L300" class="LineNr">300 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L301" class="LineNr">301 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L302" class="LineNr">302 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L303" class="LineNr">303 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L304" class="LineNr">304 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L305" class="LineNr">305 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L306" class="LineNr">306 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
 <span id="L307" class="LineNr">307 </span>  ]
-<span id="L308" class="LineNr">308 </span>  run [
-<span id="L309" class="LineNr">309 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L310" class="LineNr">310 </span>  ]
-<span id="L311" class="LineNr">311 </span>  <span class="Comment"># it copies into recipe side</span>
-<span id="L312" class="LineNr">312 </span>  screen-should-contain [
-<span id="L313" class="LineNr">313 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L314" class="LineNr">314 </span>  <span class="Conceal">¦</span><span class="Constant"> .add 1, 1                                          ╎                                                 .</span>
-<span id="L315" class="LineNr">315 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L316" class="LineNr">316 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L317" class="LineNr">317 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎add 1, 1                                         .</span>
-<span id="L318" class="LineNr">318 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L308" class="LineNr">308 </span>  <span class="Comment"># click at left edge of 'copy' button</span>
+<span id="L309" class="LineNr">309 </span>  assume-console [
+<span id="L310" class="LineNr">310 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 78</span>
+<span id="L311" class="LineNr">311 </span>  ]
+<span id="L312" class="LineNr">312 </span>  run [
+<span id="L313" class="LineNr">313 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L314" class="LineNr">314 </span>  ]
+<span id="L315" class="LineNr">315 </span>  <span class="Comment"># it copies into recipe side</span>
+<span id="L316" class="LineNr">316 </span>  screen-should-contain [
+<span id="L317" class="LineNr">317 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L318" class="LineNr">318 </span>  <span class="Conceal">¦</span><span class="Constant"> .add 1, 1                                          ╎                                                 .</span>
 <span id="L319" class="LineNr">319 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L320" class="LineNr">320 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L321" class="LineNr">321 </span>  ]
-<span id="L322" class="LineNr">322 </span>  <span class="Comment"># cursor should be at the top left of the recipe side</span>
-<span id="L323" class="LineNr">323 </span>  assume-console [
-<span id="L324" class="LineNr">324 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
+<span id="L320" class="LineNr">320 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L321" class="LineNr">321 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎add 1, 1                                         .</span>
+<span id="L322" class="LineNr">322 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L323" class="LineNr">323 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L324" class="LineNr">324 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
 <span id="L325" class="LineNr">325 </span>  ]
-<span id="L326" class="LineNr">326 </span>  run [
-<span id="L327" class="LineNr">327 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L328" class="LineNr">328 </span>  ]
-<span id="L329" class="LineNr">329 </span>  screen-should-contain [
-<span id="L330" class="LineNr">330 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L331" class="LineNr">331 </span>  <span class="Conceal">¦</span><span class="Constant"> .0add 1, 1                                         ╎                                                 .</span>
-<span id="L332" class="LineNr">332 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L333" class="LineNr">333 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L334" class="LineNr">334 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎add 1, 1                                         .</span>
-<span id="L335" class="LineNr">335 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L326" class="LineNr">326 </span>  <span class="Comment"># cursor should be at the top left of the recipe side</span>
+<span id="L327" class="LineNr">327 </span>  assume-console [
+<span id="L328" class="LineNr">328 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
+<span id="L329" class="LineNr">329 </span>  ]
+<span id="L330" class="LineNr">330 </span>  run [
+<span id="L331" class="LineNr">331 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L332" class="LineNr">332 </span>  ]
+<span id="L333" class="LineNr">333 </span>  screen-should-contain [
+<span id="L334" class="LineNr">334 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L335" class="LineNr">335 </span>  <span class="Conceal">¦</span><span class="Constant"> .0add 1, 1                                         ╎                                                 .</span>
 <span id="L336" class="LineNr">336 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L337" class="LineNr">337 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L338" class="LineNr">338 </span>  ]
-<span id="L339" class="LineNr">339 </span>]
-<span id="L340" class="LineNr">340 </span>
-<span id="L341" class="LineNr">341 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
-<span id="L342" class="LineNr">342 </span>  <span class="Comment"># support 'copy to recipe' button</span>
-<span id="L343" class="LineNr">343 </span>  <span class="Delimiter">{</span>
-<span id="L344" class="LineNr">344 </span>  <span class="Conceal">¦</span> copy?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L356'>should-copy-to-recipe?</a> click-row, click-column, env
-<span id="L345" class="LineNr">345 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> copy?
-<span id="L346" class="LineNr">346 </span>  <span class="Conceal">¦</span> modified?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L371'>prepend-sandbox-into-recipe-side</a> click-row, env
-<span id="L347" class="LineNr">347 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> modified?
-<span id="L348" class="LineNr">348 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox-in-focus?:offset</span>, <span class="Constant">0/false</span>
-<span id="L349" class="LineNr">349 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L432'>render-recipes</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L350" class="LineNr">350 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L351" class="LineNr">351 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L352" class="LineNr">352 </span>  <span class="Delimiter">}</span>
-<span id="L353" class="LineNr">353 </span>]
-<span id="L354" class="LineNr">354 </span>
-<span id="L355" class="LineNr">355 </span><span class="Comment"># some preconditions for attempting to copy a sandbox into the recipe side</span>
-<span id="L356" class="LineNr">356 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L356'>should-copy-to-recipe?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
-<span id="L357" class="LineNr">357 </span>  <span class="Constant">local-scope</span>
-<span id="L358" class="LineNr">358 </span>  <span class="Constant">load-ingredients</span>
-<span id="L359" class="LineNr">359 </span>  <span class="Comment"># are we below the sandbox editor?</span>
-<span id="L360" class="LineNr">360 </span>  click-sandbox-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L188'>click-on-sandbox-area?</a> click-row, click-column, env
-<span id="L361" class="LineNr">361 </span>  <span class="muControl">return-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
-<span id="L362" class="LineNr">362 </span>  <span class="Comment"># narrower, is the click in the columns spanning the 'copy' button?</span>
-<span id="L363" class="LineNr">363 </span>  first-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L364" class="LineNr">364 </span>  assert first-sandbox, <span class="Constant">[!!]</span>
-<span id="L365" class="LineNr">365 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">left:offset</span>
-<span id="L366" class="LineNr">366 </span>  sandbox-right-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">right:offset</span>
-<span id="L367" class="LineNr">367 </span>  _, _, _, _, recipe-button-left:num, recipe-button-right:num <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L340'>sandbox-menu-columns</a> sandbox-left-margin, sandbox-right-margin
-<span id="L368" class="LineNr">368 </span>  result <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L209'>within-range?</a> click-column, recipe-button-left, recipe-button-right
-<span id="L369" class="LineNr">369 </span>]
-<span id="L370" class="LineNr">370 </span>
-<span id="L371" class="LineNr">371 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L371'>prepend-sandbox-into-recipe-side</a> click-row:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>clicked-on-copy-to-recipe-button?:bool, env:&amp;:environment [
-<span id="L372" class="LineNr">372 </span>  <span class="Constant">local-scope</span>
-<span id="L373" class="LineNr">373 </span>  <span class="Constant">load-ingredients</span>
-<span id="L374" class="LineNr">374 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L173'>find-sandbox</a> env, click-row
-<span id="L375" class="LineNr">375 </span>  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
-<span id="L376" class="LineNr">376 </span>  recipe-editor:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">recipes:offset</span>
-<span id="L377" class="LineNr">377 </span>  recipe-data:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> get *recipe-editor, <span class="Constant">data:offset</span>
-<span id="L378" class="LineNr">378 </span>  <span class="Comment"># make the newly inserted code easy to delineate</span>
-<span id="L379" class="LineNr">379 </span>  newline:char <span class="Special">&lt;-</span> copy<span class="Constant"> 10</span>
-<span id="L380" class="LineNr">380 </span>  insert newline, recipe-data
-<span id="L381" class="LineNr">381 </span>  insert newline, recipe-data
-<span id="L382" class="LineNr">382 </span>  <span class="Comment"># insert code from the selected sandbox</span>
-<span id="L383" class="LineNr">383 </span>  sandbox-data:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
-<span id="L384" class="LineNr">384 </span>  insert recipe-data, sandbox-data
-<span id="L385" class="LineNr">385 </span>  <span class="Comment"># reset cursor</span>
-<span id="L386" class="LineNr">386 </span>  *recipe-editor <span class="Special">&lt;-</span> put *recipe-editor, <span class="Constant">top-of-screen:offset</span>, recipe-data
-<span id="L387" class="LineNr">387 </span>  *recipe-editor <span class="Special">&lt;-</span> put *recipe-editor, <span class="Constant">before-cursor:offset</span>, recipe-data
-<span id="L388" class="LineNr">388 </span>  *recipe-editor <span class="Special">&lt;-</span> put *recipe-editor, <span class="Constant">cursor-row:offset</span>,<span class="Constant"> 1</span>
-<span id="L389" class="LineNr">389 </span>  *recipe-editor <span class="Special">&lt;-</span> put *recipe-editor, <span class="Constant">cursor-column:offset</span>,<span class="Constant"> 0</span>
-<span id="L390" class="LineNr">390 </span>  <span class="muControl">return</span> <span class="Constant">1/true</span>
-<span id="L391" class="LineNr">391 </span>]
+<span id="L337" class="LineNr">337 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L338" class="LineNr">338 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎add 1, 1                                         .</span>
+<span id="L339" class="LineNr">339 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L340" class="LineNr">340 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L341" class="LineNr">341 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L342" class="LineNr">342 </span>  ]
+<span id="L343" class="LineNr">343 </span>]
+<span id="L344" class="LineNr">344 </span>
+<span id="L345" class="LineNr">345 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
+<span id="L346" class="LineNr">346 </span>  <span class="Comment"># support 'copy to recipe' button</span>
+<span id="L347" class="LineNr">347 </span>  <span class="Delimiter">{</span>
+<span id="L348" class="LineNr">348 </span>  <span class="Conceal">¦</span> copy?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L360'>should-copy-to-recipe?</a> click-row, click-column, env
+<span id="L349" class="LineNr">349 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> copy?
+<span id="L350" class="LineNr">350 </span>  <span class="Conceal">¦</span> modified?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L375'>prepend-sandbox-into-recipe-side</a> click-row, env
+<span id="L351" class="LineNr">351 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> modified?
+<span id="L352" class="LineNr">352 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox-in-focus?:offset</span>, <span class="Constant">0/false</span>
+<span id="L353" class="LineNr">353 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L432'>render-recipes</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L354" class="LineNr">354 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L355" class="LineNr">355 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L356" class="LineNr">356 </span>  <span class="Delimiter">}</span>
+<span id="L357" class="LineNr">357 </span>]
+<span id="L358" class="LineNr">358 </span>
+<span id="L359" class="LineNr">359 </span><span class="Comment"># some preconditions for attempting to copy a sandbox into the recipe side</span>
+<span id="L360" class="LineNr">360 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L360'>should-copy-to-recipe?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
+<span id="L361" class="LineNr">361 </span>  <span class="Constant">local-scope</span>
+<span id="L362" class="LineNr">362 </span>  <span class="Constant">load-ingredients</span>
+<span id="L363" class="LineNr">363 </span>  <span class="Comment"># are we below the sandbox editor?</span>
+<span id="L364" class="LineNr">364 </span>  click-sandbox-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L190'>click-on-sandbox-area?</a> click-row, click-column, env
+<span id="L365" class="LineNr">365 </span>  <span class="muControl">return-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
+<span id="L366" class="LineNr">366 </span>  <span class="Comment"># narrower, is the click in the columns spanning the 'copy' button?</span>
+<span id="L367" class="LineNr">367 </span>  first-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L368" class="LineNr">368 </span>  assert first-sandbox, <span class="Constant">[!!]</span>
+<span id="L369" class="LineNr">369 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">left:offset</span>
+<span id="L370" class="LineNr">370 </span>  sandbox-right-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">right:offset</span>
+<span id="L371" class="LineNr">371 </span>  _, _, _, _, recipe-button-left:num, recipe-button-right:num <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L346'>sandbox-menu-columns</a> sandbox-left-margin, sandbox-right-margin
+<span id="L372" class="LineNr">372 </span>  result <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L211'>within-range?</a> click-column, recipe-button-left, recipe-button-right
+<span id="L373" class="LineNr">373 </span>]
+<span id="L374" class="LineNr">374 </span>
+<span id="L375" class="LineNr">375 </span><span class="muRecipe">def</span> <a href='006-sandbox-copy.mu.html#L375'>prepend-sandbox-into-recipe-side</a> click-row:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>clicked-on-copy-to-recipe-button?:bool, env:&amp;:environment [
+<span id="L376" class="LineNr">376 </span>  <span class="Constant">local-scope</span>
+<span id="L377" class="LineNr">377 </span>  <span class="Constant">load-ingredients</span>
+<span id="L378" class="LineNr">378 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L175'>find-sandbox</a> env, click-row
+<span id="L379" class="LineNr">379 </span>  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
+<span id="L380" class="LineNr">380 </span>  recipe-editor:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">recipes:offset</span>
+<span id="L381" class="LineNr">381 </span>  recipe-data:&amp;:<a href='../065duplex_list.mu.html#L3'>duplex-list</a>:char <span class="Special">&lt;-</span> get *recipe-editor, <span class="Constant">data:offset</span>
+<span id="L382" class="LineNr">382 </span>  <span class="Comment"># make the newly inserted code easy to delineate</span>
+<span id="L383" class="LineNr">383 </span>  newline:char <span class="Special">&lt;-</span> copy<span class="Constant"> 10</span>
+<span id="L384" class="LineNr">384 </span>  insert newline, recipe-data
+<span id="L385" class="LineNr">385 </span>  insert newline, recipe-data
+<span id="L386" class="LineNr">386 </span>  <span class="Comment"># insert code from the selected sandbox</span>
+<span id="L387" class="LineNr">387 </span>  sandbox-data:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
+<span id="L388" class="LineNr">388 </span>  insert recipe-data, sandbox-data
+<span id="L389" class="LineNr">389 </span>  <span class="Comment"># reset cursor</span>
+<span id="L390" class="LineNr">390 </span>  *recipe-editor <span class="Special">&lt;-</span> put *recipe-editor, <span class="Constant">top-of-screen:offset</span>, recipe-data
+<span id="L391" class="LineNr">391 </span>  *recipe-editor <span class="Special">&lt;-</span> put *recipe-editor, <span class="Constant">before-cursor:offset</span>, recipe-data
+<span id="L392" class="LineNr">392 </span>  *recipe-editor <span class="Special">&lt;-</span> put *recipe-editor, <span class="Constant">cursor-row:offset</span>,<span class="Constant"> 1</span>
+<span id="L393" class="LineNr">393 </span>  *recipe-editor <span class="Special">&lt;-</span> put *recipe-editor, <span class="Constant">cursor-column:offset</span>,<span class="Constant"> 0</span>
+<span id="L394" class="LineNr">394 </span>  <span class="muControl">return</span> <span class="Constant">1/true</span>
+<span id="L395" class="LineNr">395 </span>]
 </pre>
 </body>
 </html>
diff --git a/html/edit/007-sandbox-delete.mu.html b/html/edit/007-sandbox-delete.mu.html
index 8fce15fb..4ec25354 100644
--- a/html/edit/007-sandbox-delete.mu.html
+++ b/html/edit/007-sandbox-delete.mu.html
@@ -69,338 +69,339 @@ if ('onhashchange' in window) {
 <span id="L7" class="LineNr">  7 </span>  assume-resources [
 <span id="L8" class="LineNr">  8 </span>  ]
 <span id="L9" class="LineNr">  9 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L10" class="LineNr"> 10 </span>  <span class="Comment"># run a few commands</span>
-<span id="L11" class="LineNr"> 11 </span>  assume-console [
-<span id="L12" class="LineNr"> 12 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 1</span>,<span class="Constant"> 75</span>
-<span id="L13" class="LineNr"> 13 </span>  <span class="Conceal">¦</span> type <span class="Constant">[divide-with-remainder 11, 3]</span>
-<span id="L14" class="LineNr"> 14 </span>  <span class="Conceal">¦</span> press F4
-<span id="L15" class="LineNr"> 15 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L16" class="LineNr"> 16 </span>  <span class="Conceal">¦</span> press F4
-<span id="L17" class="LineNr"> 17 </span>  ]
-<span id="L18" class="LineNr"> 18 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L19" class="LineNr"> 19 </span>  screen-should-contain [
-<span id="L20" class="LineNr"> 20 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L21" class="LineNr"> 21 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L22" class="LineNr"> 22 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L23" class="LineNr"> 23 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L25" class="LineNr"> 25 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L26" class="LineNr"> 26 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L27" class="LineNr"> 27 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L28" class="LineNr"> 28 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎divide-with-remainder 11, 3                      .</span>
-<span id="L29" class="LineNr"> 29 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎3                                                .</span>
-<span id="L30" class="LineNr"> 30 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L31" class="LineNr"> 31 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L32" class="LineNr"> 32 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L33" class="LineNr"> 33 </span>  ]
-<span id="L34" class="LineNr"> 34 </span>  <span class="Comment"># delete second sandbox by clicking on left edge of 'delete' button</span>
-<span id="L35" class="LineNr"> 35 </span>  assume-console [
-<span id="L36" class="LineNr"> 36 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 7</span>,<span class="Constant"> 90</span>
-<span id="L37" class="LineNr"> 37 </span>  ]
-<span id="L38" class="LineNr"> 38 </span>  run [
-<span id="L39" class="LineNr"> 39 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L40" class="LineNr"> 40 </span>  ]
-<span id="L41" class="LineNr"> 41 </span>  screen-should-contain [
-<span id="L42" class="LineNr"> 42 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L43" class="LineNr"> 43 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L44" class="LineNr"> 44 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L45" class="LineNr"> 45 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L46" class="LineNr"> 46 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L47" class="LineNr"> 47 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L48" class="LineNr"> 48 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L49" class="LineNr"> 49 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L10" class="LineNr"> 10 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L11" class="LineNr"> 11 </span>  <span class="Comment"># run a few commands</span>
+<span id="L12" class="LineNr"> 12 </span>  assume-console [
+<span id="L13" class="LineNr"> 13 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 1</span>,<span class="Constant"> 75</span>
+<span id="L14" class="LineNr"> 14 </span>  <span class="Conceal">¦</span> type <span class="Constant">[divide-with-remainder 11, 3]</span>
+<span id="L15" class="LineNr"> 15 </span>  <span class="Conceal">¦</span> press F4
+<span id="L16" class="LineNr"> 16 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L17" class="LineNr"> 17 </span>  <span class="Conceal">¦</span> press F4
+<span id="L18" class="LineNr"> 18 </span>  ]
+<span id="L19" class="LineNr"> 19 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L20" class="LineNr"> 20 </span>  screen-should-contain [
+<span id="L21" class="LineNr"> 21 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L22" class="LineNr"> 22 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L23" class="LineNr"> 23 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L25" class="LineNr"> 25 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L26" class="LineNr"> 26 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L27" class="LineNr"> 27 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L28" class="LineNr"> 28 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L29" class="LineNr"> 29 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎divide-with-remainder 11, 3                      .</span>
+<span id="L30" class="LineNr"> 30 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎3                                                .</span>
+<span id="L31" class="LineNr"> 31 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L32" class="LineNr"> 32 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L33" class="LineNr"> 33 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L34" class="LineNr"> 34 </span>  ]
+<span id="L35" class="LineNr"> 35 </span>  <span class="Comment"># delete second sandbox by clicking on left edge of 'delete' button</span>
+<span id="L36" class="LineNr"> 36 </span>  assume-console [
+<span id="L37" class="LineNr"> 37 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 7</span>,<span class="Constant"> 90</span>
+<span id="L38" class="LineNr"> 38 </span>  ]
+<span id="L39" class="LineNr"> 39 </span>  run [
+<span id="L40" class="LineNr"> 40 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L41" class="LineNr"> 41 </span>  ]
+<span id="L42" class="LineNr"> 42 </span>  screen-should-contain [
+<span id="L43" class="LineNr"> 43 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L44" class="LineNr"> 44 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L45" class="LineNr"> 45 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L46" class="LineNr"> 46 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L47" class="LineNr"> 47 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L48" class="LineNr"> 48 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L49" class="LineNr"> 49 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
 <span id="L50" class="LineNr"> 50 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L51" class="LineNr"> 51 </span>  ]
-<span id="L52" class="LineNr"> 52 </span>  <span class="Comment"># delete first sandbox by clicking at right edge of 'delete' button</span>
-<span id="L53" class="LineNr"> 53 </span>  assume-console [
-<span id="L54" class="LineNr"> 54 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 99</span>
-<span id="L55" class="LineNr"> 55 </span>  ]
-<span id="L56" class="LineNr"> 56 </span>  run [
-<span id="L57" class="LineNr"> 57 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L58" class="LineNr"> 58 </span>  ]
-<span id="L59" class="LineNr"> 59 </span>  screen-should-contain [
-<span id="L60" class="LineNr"> 60 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L61" class="LineNr"> 61 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L62" class="LineNr"> 62 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L63" class="LineNr"> 63 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L51" class="LineNr"> 51 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L52" class="LineNr"> 52 </span>  ]
+<span id="L53" class="LineNr"> 53 </span>  <span class="Comment"># delete first sandbox by clicking at right edge of 'delete' button</span>
+<span id="L54" class="LineNr"> 54 </span>  assume-console [
+<span id="L55" class="LineNr"> 55 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 99</span>
+<span id="L56" class="LineNr"> 56 </span>  ]
+<span id="L57" class="LineNr"> 57 </span>  run [
+<span id="L58" class="LineNr"> 58 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L59" class="LineNr"> 59 </span>  ]
+<span id="L60" class="LineNr"> 60 </span>  screen-should-contain [
+<span id="L61" class="LineNr"> 61 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L62" class="LineNr"> 62 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L63" class="LineNr"> 63 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
 <span id="L64" class="LineNr"> 64 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L65" class="LineNr"> 65 </span>  ]
-<span id="L66" class="LineNr"> 66 </span>]
-<span id="L67" class="LineNr"> 67 </span>
-<span id="L68" class="LineNr"> 68 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
-<span id="L69" class="LineNr"> 69 </span>  <span class="Comment"># support 'delete' button</span>
-<span id="L70" class="LineNr"> 70 </span>  <span class="Delimiter">{</span>
-<span id="L71" class="LineNr"> 71 </span>  <span class="Conceal">¦</span> delete?:bool <span class="Special">&lt;-</span> <a href='007-sandbox-delete.mu.html#L82'>should-attempt-delete?</a> click-row, click-column, env
-<span id="L72" class="LineNr"> 72 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> delete?
-<span id="L73" class="LineNr"> 73 </span>  <span class="Conceal">¦</span> delete?, env <span class="Special">&lt;-</span> <a href='007-sandbox-delete.mu.html#L97'>try-delete-sandbox</a> click-row, env
-<span id="L74" class="LineNr"> 74 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> delete?
-<span id="L75" class="LineNr"> 75 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L76" class="LineNr"> 76 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L77" class="LineNr"> 77 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L78" class="LineNr"> 78 </span>  <span class="Delimiter">}</span>
-<span id="L79" class="LineNr"> 79 </span>]
-<span id="L80" class="LineNr"> 80 </span>
-<span id="L81" class="LineNr"> 81 </span><span class="Comment"># some preconditions for attempting to delete a sandbox</span>
-<span id="L82" class="LineNr"> 82 </span><span class="muRecipe">def</span> <a href='007-sandbox-delete.mu.html#L82'>should-attempt-delete?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
-<span id="L83" class="LineNr"> 83 </span>  <span class="Constant">local-scope</span>
-<span id="L84" class="LineNr"> 84 </span>  <span class="Constant">load-ingredients</span>
-<span id="L85" class="LineNr"> 85 </span>  <span class="Comment"># are we below the sandbox editor?</span>
-<span id="L86" class="LineNr"> 86 </span>  click-sandbox-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L188'>click-on-sandbox-area?</a> click-row, click-column, env
-<span id="L87" class="LineNr"> 87 </span>  <span class="muControl">return-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
-<span id="L88" class="LineNr"> 88 </span>  <span class="Comment"># narrower, is the click in the columns spanning the 'copy' button?</span>
-<span id="L89" class="LineNr"> 89 </span>  first-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L90" class="LineNr"> 90 </span>  assert first-sandbox, <span class="Constant">[!!]</span>
-<span id="L91" class="LineNr"> 91 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">left:offset</span>
-<span id="L92" class="LineNr"> 92 </span>  sandbox-right-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">right:offset</span>
-<span id="L93" class="LineNr"> 93 </span>  _, _, _, _, _, _, delete-button-left:num <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L340'>sandbox-menu-columns</a> sandbox-left-margin, sandbox-right-margin
-<span id="L94" class="LineNr"> 94 </span>  result <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L209'>within-range?</a> click-column, delete-button-left, sandbox-right-margin
-<span id="L95" class="LineNr"> 95 </span>]
-<span id="L96" class="LineNr"> 96 </span>
-<span id="L97" class="LineNr"> 97 </span><span class="muRecipe">def</span> <a href='007-sandbox-delete.mu.html#L97'>try-delete-sandbox</a> click-row:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>clicked-on-delete-button?:bool, env:&amp;:environment [
-<span id="L98" class="LineNr"> 98 </span>  <span class="Constant">local-scope</span>
-<span id="L99" class="LineNr"> 99 </span>  <span class="Constant">load-ingredients</span>
-<span id="L100" class="LineNr">100 </span>  <span class="Comment"># identify the sandbox to delete, if the click was actually on the 'delete' button</span>
-<span id="L101" class="LineNr">101 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L173'>find-sandbox</a> env, click-row
-<span id="L102" class="LineNr">102 </span>  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
-<span id="L103" class="LineNr">103 </span>  clicked-on-delete-button? <span class="Special">&lt;-</span> copy <span class="Constant">1/true</span>
-<span id="L104" class="LineNr">104 </span>  env <span class="Special">&lt;-</span> <a href='007-sandbox-delete.mu.html#L107'>delete-sandbox</a> env, sandbox
-<span id="L105" class="LineNr">105 </span>]
-<span id="L106" class="LineNr">106 </span>
-<span id="L107" class="LineNr">107 </span><span class="muRecipe">def</span> <a href='007-sandbox-delete.mu.html#L107'>delete-sandbox</a> env:&amp;:environment, sandbox:&amp;:sandbox<span class="muRecipe"> -&gt; </span>env:&amp;:environment [
-<span id="L108" class="LineNr">108 </span>  <span class="Constant">local-scope</span>
-<span id="L109" class="LineNr">109 </span>  <span class="Constant">load-ingredients</span>
-<span id="L110" class="LineNr">110 </span>  curr-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L111" class="LineNr">111 </span>  first-sandbox?:bool <span class="Special">&lt;-</span> equal curr-sandbox, sandbox
-<span id="L112" class="LineNr">112 </span>  <span class="Delimiter">{</span>
-<span id="L113" class="LineNr">113 </span>  <span class="Conceal">¦</span> <span class="Comment"># first sandbox? pop</span>
-<span id="L114" class="LineNr">114 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> first-sandbox?
-<span id="L115" class="LineNr">115 </span>  <span class="Conceal">¦</span> next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
-<span id="L116" class="LineNr">116 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox:offset</span>, next-sandbox
-<span id="L117" class="LineNr">117 </span>  <span class="Delimiter">}</span>
-<span id="L118" class="LineNr">118 </span>  <span class="Delimiter">{</span>
-<span id="L119" class="LineNr">119 </span>  <span class="Conceal">¦</span> <span class="Comment"># not first sandbox?</span>
-<span id="L120" class="LineNr">120 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> first-sandbox?
-<span id="L121" class="LineNr">121 </span>  <span class="Conceal">¦</span> prev-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> copy curr-sandbox
-<span id="L122" class="LineNr">122 </span>  <span class="Conceal">¦</span> curr-sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
-<span id="L123" class="LineNr">123 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L124" class="LineNr">124 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> assert curr-sandbox, <span class="Constant">[sandbox not found! something is wrong.]</span>
-<span id="L125" class="LineNr">125 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> equal curr-sandbox, sandbox
-<span id="L126" class="LineNr">126 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> found?
-<span id="L127" class="LineNr">127 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> prev-sandbox <span class="Special">&lt;-</span> copy curr-sandbox
-<span id="L128" class="LineNr">128 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> curr-sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
-<span id="L129" class="LineNr">129 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L130" class="LineNr">130 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L131" class="LineNr">131 </span>  <span class="Conceal">¦</span> <span class="Comment"># snip sandbox out of its list</span>
-<span id="L132" class="LineNr">132 </span>  <span class="Conceal">¦</span> next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
-<span id="L133" class="LineNr">133 </span>  <span class="Conceal">¦</span> *prev-sandbox <span class="Special">&lt;-</span> put *prev-sandbox, <span class="Constant">next-sandbox:offset</span>, next-sandbox
-<span id="L134" class="LineNr">134 </span>  <span class="Delimiter">}</span>
-<span id="L135" class="LineNr">135 </span>  <span class="Comment"># update sandbox count</span>
-<span id="L136" class="LineNr">136 </span>  sandbox-count:num <span class="Special">&lt;-</span> get *env, <span class="Constant">number-of-sandboxes:offset</span>
-<span id="L137" class="LineNr">137 </span>  sandbox-count <span class="Special">&lt;-</span> subtract sandbox-count,<span class="Constant"> 1</span>
-<span id="L138" class="LineNr">138 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">number-of-sandboxes:offset</span>, sandbox-count
-<span id="L139" class="LineNr">139 </span>  <span class="Comment"># reset scroll if deleted sandbox was last</span>
-<span id="L140" class="LineNr">140 </span>  <span class="Delimiter">{</span>
-<span id="L141" class="LineNr">141 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> next-sandbox
-<span id="L142" class="LineNr">142 </span>  <span class="Conceal">¦</span> render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
-<span id="L143" class="LineNr">143 </span>  <span class="Conceal">¦</span> reset-scroll?:bool <span class="Special">&lt;-</span> equal render-from, sandbox-count
-<span id="L144" class="LineNr">144 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> reset-scroll?
-<span id="L145" class="LineNr">145 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>,<span class="Constant"> -1</span>
-<span id="L146" class="LineNr">146 </span>  <span class="Delimiter">}</span>
-<span id="L147" class="LineNr">147 </span>]
-<span id="L148" class="LineNr">148 </span>
-<span id="L149" class="LineNr">149 </span><span class="muScenario">scenario</span> deleting-sandbox-after-scroll [
-<span id="L150" class="LineNr">150 </span>  <span class="Constant">local-scope</span>
-<span id="L151" class="LineNr">151 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L152" class="LineNr">152 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L153" class="LineNr">153 </span>  <span class="Comment"># initialize environment</span>
-<span id="L154" class="LineNr">154 </span>  assume-resources [
-<span id="L155" class="LineNr">155 </span>  ]
-<span id="L156" class="LineNr">156 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L157" class="LineNr">157 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L158" class="LineNr">158 </span>  <span class="Comment"># create 2 sandboxes and scroll to second</span>
-<span id="L159" class="LineNr">159 </span>  assume-console [
-<span id="L160" class="LineNr">160 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L161" class="LineNr">161 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L162" class="LineNr">162 </span>  <span class="Conceal">¦</span> press F4
-<span id="L163" class="LineNr">163 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
-<span id="L164" class="LineNr">164 </span>  <span class="Conceal">¦</span> press F4
-<span id="L165" class="LineNr">165 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L166" class="LineNr">166 </span>  ]
-<span id="L167" class="LineNr">167 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L168" class="LineNr">168 </span>  screen-should-contain [
-<span id="L169" class="LineNr">169 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L170" class="LineNr">170 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L171" class="LineNr">171 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
-<span id="L172" class="LineNr">172 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L173" class="LineNr">173 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L174" class="LineNr">174 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L175" class="LineNr">175 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L176" class="LineNr">176 </span>  ]
-<span id="L177" class="LineNr">177 </span>  <span class="Comment"># delete the second sandbox</span>
-<span id="L178" class="LineNr">178 </span>  assume-console [
-<span id="L179" class="LineNr">179 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 6</span>,<span class="Constant"> 99</span>
-<span id="L180" class="LineNr">180 </span>  ]
-<span id="L181" class="LineNr">181 </span>  run [
-<span id="L182" class="LineNr">182 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L183" class="LineNr">183 </span>  ]
-<span id="L184" class="LineNr">184 </span>  <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
-<span id="L185" class="LineNr">185 </span>  screen-should-contain [
-<span id="L186" class="LineNr">186 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L187" class="LineNr">187 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L188" class="LineNr">188 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
-<span id="L189" class="LineNr">189 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L190" class="LineNr">190 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L191" class="LineNr">191 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L192" class="LineNr">192 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L193" class="LineNr">193 </span>  ]
-<span id="L194" class="LineNr">194 </span>]
-<span id="L195" class="LineNr">195 </span>
-<span id="L196" class="LineNr">196 </span><span class="muScenario">scenario</span> deleting-top-sandbox-after-scroll [
-<span id="L197" class="LineNr">197 </span>  <span class="Constant">local-scope</span>
-<span id="L198" class="LineNr">198 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L199" class="LineNr">199 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L200" class="LineNr">200 </span>  <span class="Comment"># initialize environment</span>
-<span id="L201" class="LineNr">201 </span>  assume-resources [
-<span id="L202" class="LineNr">202 </span>  ]
-<span id="L203" class="LineNr">203 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L204" class="LineNr">204 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L205" class="LineNr">205 </span>  <span class="Comment"># create 2 sandboxes and scroll to second</span>
-<span id="L206" class="LineNr">206 </span>  assume-console [
-<span id="L207" class="LineNr">207 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L208" class="LineNr">208 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L209" class="LineNr">209 </span>  <span class="Conceal">¦</span> press F4
-<span id="L210" class="LineNr">210 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
-<span id="L211" class="LineNr">211 </span>  <span class="Conceal">¦</span> press F4
-<span id="L212" class="LineNr">212 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L213" class="LineNr">213 </span>  ]
-<span id="L214" class="LineNr">214 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L215" class="LineNr">215 </span>  screen-should-contain [
-<span id="L216" class="LineNr">216 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L217" class="LineNr">217 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L218" class="LineNr">218 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
-<span id="L219" class="LineNr">219 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L220" class="LineNr">220 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L221" class="LineNr">221 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L222" class="LineNr">222 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L223" class="LineNr">223 </span>  ]
-<span id="L224" class="LineNr">224 </span>  <span class="Comment"># delete the second sandbox</span>
-<span id="L225" class="LineNr">225 </span>  assume-console [
-<span id="L226" class="LineNr">226 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 99</span>
-<span id="L227" class="LineNr">227 </span>  ]
-<span id="L228" class="LineNr">228 </span>  run [
-<span id="L229" class="LineNr">229 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L230" class="LineNr">230 </span>  ]
-<span id="L231" class="LineNr">231 </span>  <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
-<span id="L232" class="LineNr">232 </span>  screen-should-contain [
-<span id="L233" class="LineNr">233 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L234" class="LineNr">234 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L235" class="LineNr">235 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
-<span id="L236" class="LineNr">236 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L237" class="LineNr">237 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L238" class="LineNr">238 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L239" class="LineNr">239 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L240" class="LineNr">240 </span>  ]
-<span id="L241" class="LineNr">241 </span>]
-<span id="L242" class="LineNr">242 </span>
-<span id="L243" class="LineNr">243 </span><span class="muScenario">scenario</span> deleting-final-sandbox-after-scroll [
-<span id="L244" class="LineNr">244 </span>  <span class="Constant">local-scope</span>
-<span id="L245" class="LineNr">245 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L246" class="LineNr">246 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L247" class="LineNr">247 </span>  <span class="Comment"># initialize environment</span>
-<span id="L248" class="LineNr">248 </span>  assume-resources [
-<span id="L249" class="LineNr">249 </span>  ]
-<span id="L250" class="LineNr">250 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L251" class="LineNr">251 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L252" class="LineNr">252 </span>  <span class="Comment"># create 2 sandboxes and scroll to second</span>
-<span id="L253" class="LineNr">253 </span>  assume-console [
-<span id="L254" class="LineNr">254 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L255" class="LineNr">255 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L256" class="LineNr">256 </span>  <span class="Conceal">¦</span> press F4
-<span id="L257" class="LineNr">257 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
-<span id="L258" class="LineNr">258 </span>  <span class="Conceal">¦</span> press F4
-<span id="L259" class="LineNr">259 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L65" class="LineNr"> 65 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L66" class="LineNr"> 66 </span>  ]
+<span id="L67" class="LineNr"> 67 </span>]
+<span id="L68" class="LineNr"> 68 </span>
+<span id="L69" class="LineNr"> 69 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
+<span id="L70" class="LineNr"> 70 </span>  <span class="Comment"># support 'delete' button</span>
+<span id="L71" class="LineNr"> 71 </span>  <span class="Delimiter">{</span>
+<span id="L72" class="LineNr"> 72 </span>  <span class="Conceal">¦</span> delete?:bool <span class="Special">&lt;-</span> <a href='007-sandbox-delete.mu.html#L83'>should-attempt-delete?</a> click-row, click-column, env
+<span id="L73" class="LineNr"> 73 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> delete?
+<span id="L74" class="LineNr"> 74 </span>  <span class="Conceal">¦</span> delete?, env <span class="Special">&lt;-</span> <a href='007-sandbox-delete.mu.html#L98'>try-delete-sandbox</a> click-row, env
+<span id="L75" class="LineNr"> 75 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> delete?
+<span id="L76" class="LineNr"> 76 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L77" class="LineNr"> 77 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L78" class="LineNr"> 78 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L79" class="LineNr"> 79 </span>  <span class="Delimiter">}</span>
+<span id="L80" class="LineNr"> 80 </span>]
+<span id="L81" class="LineNr"> 81 </span>
+<span id="L82" class="LineNr"> 82 </span><span class="Comment"># some preconditions for attempting to delete a sandbox</span>
+<span id="L83" class="LineNr"> 83 </span><span class="muRecipe">def</span> <a href='007-sandbox-delete.mu.html#L83'>should-attempt-delete?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
+<span id="L84" class="LineNr"> 84 </span>  <span class="Constant">local-scope</span>
+<span id="L85" class="LineNr"> 85 </span>  <span class="Constant">load-ingredients</span>
+<span id="L86" class="LineNr"> 86 </span>  <span class="Comment"># are we below the sandbox editor?</span>
+<span id="L87" class="LineNr"> 87 </span>  click-sandbox-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L190'>click-on-sandbox-area?</a> click-row, click-column, env
+<span id="L88" class="LineNr"> 88 </span>  <span class="muControl">return-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
+<span id="L89" class="LineNr"> 89 </span>  <span class="Comment"># narrower, is the click in the columns spanning the 'copy' button?</span>
+<span id="L90" class="LineNr"> 90 </span>  first-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L91" class="LineNr"> 91 </span>  assert first-sandbox, <span class="Constant">[!!]</span>
+<span id="L92" class="LineNr"> 92 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">left:offset</span>
+<span id="L93" class="LineNr"> 93 </span>  sandbox-right-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">right:offset</span>
+<span id="L94" class="LineNr"> 94 </span>  _, _, _, _, _, _, delete-button-left:num <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L346'>sandbox-menu-columns</a> sandbox-left-margin, sandbox-right-margin
+<span id="L95" class="LineNr"> 95 </span>  result <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L211'>within-range?</a> click-column, delete-button-left, sandbox-right-margin
+<span id="L96" class="LineNr"> 96 </span>]
+<span id="L97" class="LineNr"> 97 </span>
+<span id="L98" class="LineNr"> 98 </span><span class="muRecipe">def</span> <a href='007-sandbox-delete.mu.html#L98'>try-delete-sandbox</a> click-row:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>clicked-on-delete-button?:bool, env:&amp;:environment [
+<span id="L99" class="LineNr"> 99 </span>  <span class="Constant">local-scope</span>
+<span id="L100" class="LineNr">100 </span>  <span class="Constant">load-ingredients</span>
+<span id="L101" class="LineNr">101 </span>  <span class="Comment"># identify the sandbox to delete, if the click was actually on the 'delete' button</span>
+<span id="L102" class="LineNr">102 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L175'>find-sandbox</a> env, click-row
+<span id="L103" class="LineNr">103 </span>  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
+<span id="L104" class="LineNr">104 </span>  clicked-on-delete-button? <span class="Special">&lt;-</span> copy <span class="Constant">1/true</span>
+<span id="L105" class="LineNr">105 </span>  env <span class="Special">&lt;-</span> <a href='007-sandbox-delete.mu.html#L108'>delete-sandbox</a> env, sandbox
+<span id="L106" class="LineNr">106 </span>]
+<span id="L107" class="LineNr">107 </span>
+<span id="L108" class="LineNr">108 </span><span class="muRecipe">def</span> <a href='007-sandbox-delete.mu.html#L108'>delete-sandbox</a> env:&amp;:environment, sandbox:&amp;:sandbox<span class="muRecipe"> -&gt; </span>env:&amp;:environment [
+<span id="L109" class="LineNr">109 </span>  <span class="Constant">local-scope</span>
+<span id="L110" class="LineNr">110 </span>  <span class="Constant">load-ingredients</span>
+<span id="L111" class="LineNr">111 </span>  curr-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L112" class="LineNr">112 </span>  first-sandbox?:bool <span class="Special">&lt;-</span> equal curr-sandbox, sandbox
+<span id="L113" class="LineNr">113 </span>  <span class="Delimiter">{</span>
+<span id="L114" class="LineNr">114 </span>  <span class="Conceal">¦</span> <span class="Comment"># first sandbox? pop</span>
+<span id="L115" class="LineNr">115 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> first-sandbox?
+<span id="L116" class="LineNr">116 </span>  <span class="Conceal">¦</span> next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
+<span id="L117" class="LineNr">117 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox:offset</span>, next-sandbox
+<span id="L118" class="LineNr">118 </span>  <span class="Delimiter">}</span>
+<span id="L119" class="LineNr">119 </span>  <span class="Delimiter">{</span>
+<span id="L120" class="LineNr">120 </span>  <span class="Conceal">¦</span> <span class="Comment"># not first sandbox?</span>
+<span id="L121" class="LineNr">121 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> first-sandbox?
+<span id="L122" class="LineNr">122 </span>  <span class="Conceal">¦</span> prev-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> copy curr-sandbox
+<span id="L123" class="LineNr">123 </span>  <span class="Conceal">¦</span> curr-sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
+<span id="L124" class="LineNr">124 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L125" class="LineNr">125 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> assert curr-sandbox, <span class="Constant">[sandbox not found! something is wrong.]</span>
+<span id="L126" class="LineNr">126 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> equal curr-sandbox, sandbox
+<span id="L127" class="LineNr">127 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> found?
+<span id="L128" class="LineNr">128 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> prev-sandbox <span class="Special">&lt;-</span> copy curr-sandbox
+<span id="L129" class="LineNr">129 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> curr-sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
+<span id="L130" class="LineNr">130 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L131" class="LineNr">131 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L132" class="LineNr">132 </span>  <span class="Conceal">¦</span> <span class="Comment"># snip sandbox out of its list</span>
+<span id="L133" class="LineNr">133 </span>  <span class="Conceal">¦</span> next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
+<span id="L134" class="LineNr">134 </span>  <span class="Conceal">¦</span> *prev-sandbox <span class="Special">&lt;-</span> put *prev-sandbox, <span class="Constant">next-sandbox:offset</span>, next-sandbox
+<span id="L135" class="LineNr">135 </span>  <span class="Delimiter">}</span>
+<span id="L136" class="LineNr">136 </span>  <span class="Comment"># update sandbox count</span>
+<span id="L137" class="LineNr">137 </span>  sandbox-count:num <span class="Special">&lt;-</span> get *env, <span class="Constant">number-of-sandboxes:offset</span>
+<span id="L138" class="LineNr">138 </span>  sandbox-count <span class="Special">&lt;-</span> subtract sandbox-count,<span class="Constant"> 1</span>
+<span id="L139" class="LineNr">139 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">number-of-sandboxes:offset</span>, sandbox-count
+<span id="L140" class="LineNr">140 </span>  <span class="Comment"># reset scroll if deleted sandbox was last</span>
+<span id="L141" class="LineNr">141 </span>  <span class="Delimiter">{</span>
+<span id="L142" class="LineNr">142 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> next-sandbox
+<span id="L143" class="LineNr">143 </span>  <span class="Conceal">¦</span> render-from:num <span class="Special">&lt;-</span> get *env, <span class="Constant">render-from:offset</span>
+<span id="L144" class="LineNr">144 </span>  <span class="Conceal">¦</span> reset-scroll?:bool <span class="Special">&lt;-</span> equal render-from, sandbox-count
+<span id="L145" class="LineNr">145 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> reset-scroll?
+<span id="L146" class="LineNr">146 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>,<span class="Constant"> -1</span>
+<span id="L147" class="LineNr">147 </span>  <span class="Delimiter">}</span>
+<span id="L148" class="LineNr">148 </span>]
+<span id="L149" class="LineNr">149 </span>
+<span id="L150" class="LineNr">150 </span><span class="muScenario">scenario</span> deleting-sandbox-after-scroll [
+<span id="L151" class="LineNr">151 </span>  <span class="Constant">local-scope</span>
+<span id="L152" class="LineNr">152 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L153" class="LineNr">153 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L154" class="LineNr">154 </span>  <span class="Comment"># initialize environment</span>
+<span id="L155" class="LineNr">155 </span>  assume-resources [
+<span id="L156" class="LineNr">156 </span>  ]
+<span id="L157" class="LineNr">157 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L158" class="LineNr">158 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L159" class="LineNr">159 </span>  <span class="Comment"># create 2 sandboxes and scroll to second</span>
+<span id="L160" class="LineNr">160 </span>  assume-console [
+<span id="L161" class="LineNr">161 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L162" class="LineNr">162 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L163" class="LineNr">163 </span>  <span class="Conceal">¦</span> press F4
+<span id="L164" class="LineNr">164 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
+<span id="L165" class="LineNr">165 </span>  <span class="Conceal">¦</span> press F4
+<span id="L166" class="LineNr">166 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L167" class="LineNr">167 </span>  ]
+<span id="L168" class="LineNr">168 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L169" class="LineNr">169 </span>  screen-should-contain [
+<span id="L170" class="LineNr">170 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L171" class="LineNr">171 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L172" class="LineNr">172 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
+<span id="L173" class="LineNr">173 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L174" class="LineNr">174 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L175" class="LineNr">175 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L176" class="LineNr">176 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L177" class="LineNr">177 </span>  ]
+<span id="L178" class="LineNr">178 </span>  <span class="Comment"># delete the second sandbox</span>
+<span id="L179" class="LineNr">179 </span>  assume-console [
+<span id="L180" class="LineNr">180 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 6</span>,<span class="Constant"> 99</span>
+<span id="L181" class="LineNr">181 </span>  ]
+<span id="L182" class="LineNr">182 </span>  run [
+<span id="L183" class="LineNr">183 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L184" class="LineNr">184 </span>  ]
+<span id="L185" class="LineNr">185 </span>  <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
+<span id="L186" class="LineNr">186 </span>  screen-should-contain [
+<span id="L187" class="LineNr">187 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L188" class="LineNr">188 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L189" class="LineNr">189 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
+<span id="L190" class="LineNr">190 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L191" class="LineNr">191 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L192" class="LineNr">192 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L193" class="LineNr">193 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L194" class="LineNr">194 </span>  ]
+<span id="L195" class="LineNr">195 </span>]
+<span id="L196" class="LineNr">196 </span>
+<span id="L197" class="LineNr">197 </span><span class="muScenario">scenario</span> deleting-top-sandbox-after-scroll [
+<span id="L198" class="LineNr">198 </span>  <span class="Constant">local-scope</span>
+<span id="L199" class="LineNr">199 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L200" class="LineNr">200 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L201" class="LineNr">201 </span>  <span class="Comment"># initialize environment</span>
+<span id="L202" class="LineNr">202 </span>  assume-resources [
+<span id="L203" class="LineNr">203 </span>  ]
+<span id="L204" class="LineNr">204 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L205" class="LineNr">205 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L206" class="LineNr">206 </span>  <span class="Comment"># create 2 sandboxes and scroll to second</span>
+<span id="L207" class="LineNr">207 </span>  assume-console [
+<span id="L208" class="LineNr">208 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L209" class="LineNr">209 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L210" class="LineNr">210 </span>  <span class="Conceal">¦</span> press F4
+<span id="L211" class="LineNr">211 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
+<span id="L212" class="LineNr">212 </span>  <span class="Conceal">¦</span> press F4
+<span id="L213" class="LineNr">213 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L214" class="LineNr">214 </span>  ]
+<span id="L215" class="LineNr">215 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L216" class="LineNr">216 </span>  screen-should-contain [
+<span id="L217" class="LineNr">217 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L218" class="LineNr">218 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L219" class="LineNr">219 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
+<span id="L220" class="LineNr">220 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L221" class="LineNr">221 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L222" class="LineNr">222 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L223" class="LineNr">223 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L224" class="LineNr">224 </span>  ]
+<span id="L225" class="LineNr">225 </span>  <span class="Comment"># delete the second sandbox</span>
+<span id="L226" class="LineNr">226 </span>  assume-console [
+<span id="L227" class="LineNr">227 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 99</span>
+<span id="L228" class="LineNr">228 </span>  ]
+<span id="L229" class="LineNr">229 </span>  run [
+<span id="L230" class="LineNr">230 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L231" class="LineNr">231 </span>  ]
+<span id="L232" class="LineNr">232 </span>  <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
+<span id="L233" class="LineNr">233 </span>  screen-should-contain [
+<span id="L234" class="LineNr">234 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L235" class="LineNr">235 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L236" class="LineNr">236 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
+<span id="L237" class="LineNr">237 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L238" class="LineNr">238 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L239" class="LineNr">239 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L240" class="LineNr">240 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L241" class="LineNr">241 </span>  ]
+<span id="L242" class="LineNr">242 </span>]
+<span id="L243" class="LineNr">243 </span>
+<span id="L244" class="LineNr">244 </span><span class="muScenario">scenario</span> deleting-final-sandbox-after-scroll [
+<span id="L245" class="LineNr">245 </span>  <span class="Constant">local-scope</span>
+<span id="L246" class="LineNr">246 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L247" class="LineNr">247 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L248" class="LineNr">248 </span>  <span class="Comment"># initialize environment</span>
+<span id="L249" class="LineNr">249 </span>  assume-resources [
+<span id="L250" class="LineNr">250 </span>  ]
+<span id="L251" class="LineNr">251 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L252" class="LineNr">252 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L253" class="LineNr">253 </span>  <span class="Comment"># create 2 sandboxes and scroll to second</span>
+<span id="L254" class="LineNr">254 </span>  assume-console [
+<span id="L255" class="LineNr">255 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L256" class="LineNr">256 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L257" class="LineNr">257 </span>  <span class="Conceal">¦</span> press F4
+<span id="L258" class="LineNr">258 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
+<span id="L259" class="LineNr">259 </span>  <span class="Conceal">¦</span> press F4
 <span id="L260" class="LineNr">260 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L261" class="LineNr">261 </span>  ]
-<span id="L262" class="LineNr">262 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L263" class="LineNr">263 </span>  screen-should-contain [
-<span id="L264" class="LineNr">264 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L265" class="LineNr">265 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L266" class="LineNr">266 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
-<span id="L267" class="LineNr">267 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L268" class="LineNr">268 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L269" class="LineNr">269 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L270" class="LineNr">270 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L271" class="LineNr">271 </span>  ]
-<span id="L272" class="LineNr">272 </span>  <span class="Comment"># delete the second sandbox</span>
-<span id="L273" class="LineNr">273 </span>  assume-console [
-<span id="L274" class="LineNr">274 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 99</span>
-<span id="L275" class="LineNr">275 </span>  ]
-<span id="L276" class="LineNr">276 </span>  run [
-<span id="L277" class="LineNr">277 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L278" class="LineNr">278 </span>  ]
-<span id="L279" class="LineNr">279 </span>  <span class="Comment"># implicitly scroll up to first sandbox</span>
-<span id="L280" class="LineNr">280 </span>  screen-should-contain [
-<span id="L281" class="LineNr">281 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L282" class="LineNr">282 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L283" class="LineNr">283 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L284" class="LineNr">284 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L285" class="LineNr">285 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L286" class="LineNr">286 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L287" class="LineNr">287 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L288" class="LineNr">288 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L289" class="LineNr">289 </span>  ]
-<span id="L290" class="LineNr">290 </span>]
-<span id="L291" class="LineNr">291 </span>
-<span id="L292" class="LineNr">292 </span><span class="muScenario">scenario</span> deleting-updates-sandbox-count [
-<span id="L293" class="LineNr">293 </span>  <span class="Constant">local-scope</span>
-<span id="L294" class="LineNr">294 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L295" class="LineNr">295 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L296" class="LineNr">296 </span>  <span class="Comment"># initialize environment</span>
-<span id="L297" class="LineNr">297 </span>  assume-resources [
-<span id="L298" class="LineNr">298 </span>  ]
-<span id="L299" class="LineNr">299 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L300" class="LineNr">300 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L301" class="LineNr">301 </span>  <span class="Comment"># create 2 sandboxes</span>
-<span id="L302" class="LineNr">302 </span>  assume-console [
-<span id="L303" class="LineNr">303 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L304" class="LineNr">304 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L305" class="LineNr">305 </span>  <span class="Conceal">¦</span> press F4
-<span id="L306" class="LineNr">306 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
-<span id="L307" class="LineNr">307 </span>  <span class="Conceal">¦</span> press F4
-<span id="L308" class="LineNr">308 </span>  ]
-<span id="L309" class="LineNr">309 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L310" class="LineNr">310 </span>  screen-should-contain [
-<span id="L311" class="LineNr">311 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L312" class="LineNr">312 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L313" class="LineNr">313 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L314" class="LineNr">314 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L315" class="LineNr">315 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L316" class="LineNr">316 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L317" class="LineNr">317 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L318" class="LineNr">318 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L319" class="LineNr">319 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L320" class="LineNr">320 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L321" class="LineNr">321 </span>  ]
-<span id="L322" class="LineNr">322 </span>  <span class="Comment"># delete the second sandbox, then try to scroll down twice</span>
-<span id="L323" class="LineNr">323 </span>  assume-console [
-<span id="L324" class="LineNr">324 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 99</span>
-<span id="L325" class="LineNr">325 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L261" class="LineNr">261 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L262" class="LineNr">262 </span>  ]
+<span id="L263" class="LineNr">263 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L264" class="LineNr">264 </span>  screen-should-contain [
+<span id="L265" class="LineNr">265 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L266" class="LineNr">266 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L267" class="LineNr">267 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
+<span id="L268" class="LineNr">268 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L269" class="LineNr">269 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L270" class="LineNr">270 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L271" class="LineNr">271 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L272" class="LineNr">272 </span>  ]
+<span id="L273" class="LineNr">273 </span>  <span class="Comment"># delete the second sandbox</span>
+<span id="L274" class="LineNr">274 </span>  assume-console [
+<span id="L275" class="LineNr">275 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 99</span>
+<span id="L276" class="LineNr">276 </span>  ]
+<span id="L277" class="LineNr">277 </span>  run [
+<span id="L278" class="LineNr">278 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L279" class="LineNr">279 </span>  ]
+<span id="L280" class="LineNr">280 </span>  <span class="Comment"># implicitly scroll up to first sandbox</span>
+<span id="L281" class="LineNr">281 </span>  screen-should-contain [
+<span id="L282" class="LineNr">282 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L283" class="LineNr">283 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L284" class="LineNr">284 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L285" class="LineNr">285 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L286" class="LineNr">286 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L287" class="LineNr">287 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L288" class="LineNr">288 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L289" class="LineNr">289 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L290" class="LineNr">290 </span>  ]
+<span id="L291" class="LineNr">291 </span>]
+<span id="L292" class="LineNr">292 </span>
+<span id="L293" class="LineNr">293 </span><span class="muScenario">scenario</span> deleting-updates-sandbox-count [
+<span id="L294" class="LineNr">294 </span>  <span class="Constant">local-scope</span>
+<span id="L295" class="LineNr">295 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L296" class="LineNr">296 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L297" class="LineNr">297 </span>  <span class="Comment"># initialize environment</span>
+<span id="L298" class="LineNr">298 </span>  assume-resources [
+<span id="L299" class="LineNr">299 </span>  ]
+<span id="L300" class="LineNr">300 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L301" class="LineNr">301 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L302" class="LineNr">302 </span>  <span class="Comment"># create 2 sandboxes</span>
+<span id="L303" class="LineNr">303 </span>  assume-console [
+<span id="L304" class="LineNr">304 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L305" class="LineNr">305 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L306" class="LineNr">306 </span>  <span class="Conceal">¦</span> press F4
+<span id="L307" class="LineNr">307 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
+<span id="L308" class="LineNr">308 </span>  <span class="Conceal">¦</span> press F4
+<span id="L309" class="LineNr">309 </span>  ]
+<span id="L310" class="LineNr">310 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L311" class="LineNr">311 </span>  screen-should-contain [
+<span id="L312" class="LineNr">312 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L313" class="LineNr">313 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L314" class="LineNr">314 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L315" class="LineNr">315 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L316" class="LineNr">316 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L317" class="LineNr">317 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L318" class="LineNr">318 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L319" class="LineNr">319 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L320" class="LineNr">320 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L321" class="LineNr">321 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L322" class="LineNr">322 </span>  ]
+<span id="L323" class="LineNr">323 </span>  <span class="Comment"># delete the second sandbox, then try to scroll down twice</span>
+<span id="L324" class="LineNr">324 </span>  assume-console [
+<span id="L325" class="LineNr">325 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 99</span>
 <span id="L326" class="LineNr">326 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L327" class="LineNr">327 </span>  ]
-<span id="L328" class="LineNr">328 </span>  run [
-<span id="L329" class="LineNr">329 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L330" class="LineNr">330 </span>  ]
-<span id="L331" class="LineNr">331 </span>  <span class="Comment"># shouldn't go past last sandbox</span>
-<span id="L332" class="LineNr">332 </span>  screen-should-contain [
-<span id="L333" class="LineNr">333 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L334" class="LineNr">334 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L335" class="LineNr">335 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
-<span id="L336" class="LineNr">336 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L337" class="LineNr">337 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L338" class="LineNr">338 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L339" class="LineNr">339 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L340" class="LineNr">340 </span>  ]
-<span id="L341" class="LineNr">341 </span>]
+<span id="L327" class="LineNr">327 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L328" class="LineNr">328 </span>  ]
+<span id="L329" class="LineNr">329 </span>  run [
+<span id="L330" class="LineNr">330 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L331" class="LineNr">331 </span>  ]
+<span id="L332" class="LineNr">332 </span>  <span class="Comment"># shouldn't go past last sandbox</span>
+<span id="L333" class="LineNr">333 </span>  screen-should-contain [
+<span id="L334" class="LineNr">334 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L335" class="LineNr">335 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L336" class="LineNr">336 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎0   edit       copy       to recipe    delete    .</span>
+<span id="L337" class="LineNr">337 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L338" class="LineNr">338 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L339" class="LineNr">339 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L340" class="LineNr">340 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L341" class="LineNr">341 </span>  ]
+<span id="L342" class="LineNr">342 </span>]
 </pre>
 </body>
 </html>
diff --git a/html/edit/008-sandbox-edit.mu.html b/html/edit/008-sandbox-edit.mu.html
index f55c5f4f..3097c278 100644
--- a/html/edit/008-sandbox-edit.mu.html
+++ b/html/edit/008-sandbox-edit.mu.html
@@ -70,318 +70,321 @@ if ('onhashchange' in window) {
 <span id="L8" class="LineNr">  8 </span>  assume-resources [
 <span id="L9" class="LineNr">  9 </span>  ]
 <span id="L10" class="LineNr"> 10 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 2, 2]</span>
-<span id="L11" class="LineNr"> 11 </span>  <span class="Comment"># run it</span>
-<span id="L12" class="LineNr"> 12 </span>  assume-console [
-<span id="L13" class="LineNr"> 13 </span>  <span class="Conceal">¦</span> press F4
-<span id="L14" class="LineNr"> 14 </span>  ]
-<span id="L15" class="LineNr"> 15 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L16" class="LineNr"> 16 </span>  screen-should-contain [
-<span id="L17" class="LineNr"> 17 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L18" class="LineNr"> 18 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L19" class="LineNr"> 19 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L20" class="LineNr"> 20 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L21" class="LineNr"> 21 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L22" class="LineNr"> 22 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L23" class="LineNr"> 23 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L25" class="LineNr"> 25 </span>  ]
-<span id="L26" class="LineNr"> 26 </span>  <span class="Comment"># click at left edge of 'edit' button</span>
-<span id="L27" class="LineNr"> 27 </span>  assume-console [
-<span id="L28" class="LineNr"> 28 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 55</span>
-<span id="L29" class="LineNr"> 29 </span>  ]
-<span id="L30" class="LineNr"> 30 </span>  run [
-<span id="L31" class="LineNr"> 31 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L32" class="LineNr"> 32 </span>  ]
-<span id="L33" class="LineNr"> 33 </span>  <span class="Comment"># it pops back into editor</span>
-<span id="L34" class="LineNr"> 34 </span>  screen-should-contain [
-<span id="L35" class="LineNr"> 35 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L36" class="LineNr"> 36 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L37" class="LineNr"> 37 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L38" class="LineNr"> 38 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L39" class="LineNr"> 39 </span>  ]
-<span id="L40" class="LineNr"> 40 </span>  <span class="Comment"># cursor should be in the right place</span>
-<span id="L41" class="LineNr"> 41 </span>  assume-console [
-<span id="L42" class="LineNr"> 42 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
-<span id="L43" class="LineNr"> 43 </span>  ]
-<span id="L44" class="LineNr"> 44 </span>  run [
-<span id="L45" class="LineNr"> 45 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L46" class="LineNr"> 46 </span>  ]
-<span id="L47" class="LineNr"> 47 </span>  screen-should-contain [
-<span id="L48" class="LineNr"> 48 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L49" class="LineNr"> 49 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0add 2, 2                                        .</span>
-<span id="L50" class="LineNr"> 50 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L51" class="LineNr"> 51 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L52" class="LineNr"> 52 </span>  ]
-<span id="L53" class="LineNr"> 53 </span>]
-<span id="L54" class="LineNr"> 54 </span>
-<span id="L55" class="LineNr"> 55 </span><span class="muScenario">scenario</span> clicking-on-sandbox-edit-button-moves-it-to-editor-2 [
-<span id="L56" class="LineNr"> 56 </span>  <span class="Constant">local-scope</span>
-<span id="L57" class="LineNr"> 57 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L58" class="LineNr"> 58 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L59" class="LineNr"> 59 </span>  <span class="Comment"># empty recipes</span>
-<span id="L60" class="LineNr"> 60 </span>  assume-resources [
-<span id="L61" class="LineNr"> 61 </span>  ]
-<span id="L62" class="LineNr"> 62 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 2, 2]</span>
-<span id="L63" class="LineNr"> 63 </span>  <span class="Comment"># run it</span>
-<span id="L64" class="LineNr"> 64 </span>  assume-console [
-<span id="L65" class="LineNr"> 65 </span>  <span class="Conceal">¦</span> press F4
-<span id="L66" class="LineNr"> 66 </span>  ]
-<span id="L67" class="LineNr"> 67 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L68" class="LineNr"> 68 </span>  screen-should-contain [
-<span id="L69" class="LineNr"> 69 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L70" class="LineNr"> 70 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L71" class="LineNr"> 71 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L72" class="LineNr"> 72 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L73" class="LineNr"> 73 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L74" class="LineNr"> 74 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L75" class="LineNr"> 75 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L76" class="LineNr"> 76 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L77" class="LineNr"> 77 </span>  ]
-<span id="L78" class="LineNr"> 78 </span>  <span class="Comment"># click at right edge of 'edit' button (just before 'copy')</span>
-<span id="L79" class="LineNr"> 79 </span>  assume-console [
-<span id="L80" class="LineNr"> 80 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 65</span>
-<span id="L81" class="LineNr"> 81 </span>  ]
-<span id="L82" class="LineNr"> 82 </span>  run [
-<span id="L83" class="LineNr"> 83 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L84" class="LineNr"> 84 </span>  ]
-<span id="L85" class="LineNr"> 85 </span>  <span class="Comment"># it pops back into editor</span>
-<span id="L86" class="LineNr"> 86 </span>  screen-should-contain [
-<span id="L87" class="LineNr"> 87 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L88" class="LineNr"> 88 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L89" class="LineNr"> 89 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L90" class="LineNr"> 90 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L91" class="LineNr"> 91 </span>  ]
-<span id="L92" class="LineNr"> 92 </span>  <span class="Comment"># cursor should be in the right place</span>
-<span id="L93" class="LineNr"> 93 </span>  assume-console [
-<span id="L94" class="LineNr"> 94 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
-<span id="L95" class="LineNr"> 95 </span>  ]
-<span id="L96" class="LineNr"> 96 </span>  run [
-<span id="L97" class="LineNr"> 97 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L98" class="LineNr"> 98 </span>  ]
-<span id="L99" class="LineNr"> 99 </span>  screen-should-contain [
-<span id="L100" class="LineNr">100 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L101" class="LineNr">101 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0add 2, 2                                        .</span>
-<span id="L102" class="LineNr">102 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L103" class="LineNr">103 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L104" class="LineNr">104 </span>  ]
-<span id="L105" class="LineNr">105 </span>]
-<span id="L106" class="LineNr">106 </span>
-<span id="L107" class="LineNr">107 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
-<span id="L108" class="LineNr">108 </span>  <span class="Comment"># support 'edit' button</span>
-<span id="L109" class="LineNr">109 </span>  <span class="Delimiter">{</span>
-<span id="L110" class="LineNr">110 </span>  <span class="Conceal">¦</span> edit?:bool <span class="Special">&lt;-</span> <a href='008-sandbox-edit.mu.html#L121'>should-attempt-edit?</a> click-row, click-column, env
-<span id="L111" class="LineNr">111 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> edit?
-<span id="L112" class="LineNr">112 </span>  <span class="Conceal">¦</span> edit?, env <span class="Special">&lt;-</span> <a href='008-sandbox-edit.mu.html#L140'>try-edit-sandbox</a> click-row, env
+<span id="L11" class="LineNr"> 11 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L12" class="LineNr"> 12 </span>  <span class="Comment"># run it</span>
+<span id="L13" class="LineNr"> 13 </span>  assume-console [
+<span id="L14" class="LineNr"> 14 </span>  <span class="Conceal">¦</span> press F4
+<span id="L15" class="LineNr"> 15 </span>  ]
+<span id="L16" class="LineNr"> 16 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L17" class="LineNr"> 17 </span>  screen-should-contain [
+<span id="L18" class="LineNr"> 18 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L19" class="LineNr"> 19 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L20" class="LineNr"> 20 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L21" class="LineNr"> 21 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L22" class="LineNr"> 22 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L23" class="LineNr"> 23 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L25" class="LineNr"> 25 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L26" class="LineNr"> 26 </span>  ]
+<span id="L27" class="LineNr"> 27 </span>  <span class="Comment"># click at left edge of 'edit' button</span>
+<span id="L28" class="LineNr"> 28 </span>  assume-console [
+<span id="L29" class="LineNr"> 29 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 55</span>
+<span id="L30" class="LineNr"> 30 </span>  ]
+<span id="L31" class="LineNr"> 31 </span>  run [
+<span id="L32" class="LineNr"> 32 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L33" class="LineNr"> 33 </span>  ]
+<span id="L34" class="LineNr"> 34 </span>  <span class="Comment"># it pops back into editor</span>
+<span id="L35" class="LineNr"> 35 </span>  screen-should-contain [
+<span id="L36" class="LineNr"> 36 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L37" class="LineNr"> 37 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L38" class="LineNr"> 38 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L39" class="LineNr"> 39 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L40" class="LineNr"> 40 </span>  ]
+<span id="L41" class="LineNr"> 41 </span>  <span class="Comment"># cursor should be in the right place</span>
+<span id="L42" class="LineNr"> 42 </span>  assume-console [
+<span id="L43" class="LineNr"> 43 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
+<span id="L44" class="LineNr"> 44 </span>  ]
+<span id="L45" class="LineNr"> 45 </span>  run [
+<span id="L46" class="LineNr"> 46 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L47" class="LineNr"> 47 </span>  ]
+<span id="L48" class="LineNr"> 48 </span>  screen-should-contain [
+<span id="L49" class="LineNr"> 49 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L50" class="LineNr"> 50 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0add 2, 2                                        .</span>
+<span id="L51" class="LineNr"> 51 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L52" class="LineNr"> 52 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L53" class="LineNr"> 53 </span>  ]
+<span id="L54" class="LineNr"> 54 </span>]
+<span id="L55" class="LineNr"> 55 </span>
+<span id="L56" class="LineNr"> 56 </span><span class="muScenario">scenario</span> clicking-on-sandbox-edit-button-moves-it-to-editor-2 [
+<span id="L57" class="LineNr"> 57 </span>  <span class="Constant">local-scope</span>
+<span id="L58" class="LineNr"> 58 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L59" class="LineNr"> 59 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L60" class="LineNr"> 60 </span>  <span class="Comment"># empty recipes</span>
+<span id="L61" class="LineNr"> 61 </span>  assume-resources [
+<span id="L62" class="LineNr"> 62 </span>  ]
+<span id="L63" class="LineNr"> 63 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[add 2, 2]</span>
+<span id="L64" class="LineNr"> 64 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L65" class="LineNr"> 65 </span>  <span class="Comment"># run it</span>
+<span id="L66" class="LineNr"> 66 </span>  assume-console [
+<span id="L67" class="LineNr"> 67 </span>  <span class="Conceal">¦</span> press F4
+<span id="L68" class="LineNr"> 68 </span>  ]
+<span id="L69" class="LineNr"> 69 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L70" class="LineNr"> 70 </span>  screen-should-contain [
+<span id="L71" class="LineNr"> 71 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L72" class="LineNr"> 72 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L73" class="LineNr"> 73 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L74" class="LineNr"> 74 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L75" class="LineNr"> 75 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L76" class="LineNr"> 76 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L77" class="LineNr"> 77 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L78" class="LineNr"> 78 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L79" class="LineNr"> 79 </span>  ]
+<span id="L80" class="LineNr"> 80 </span>  <span class="Comment"># click at right edge of 'edit' button (just before 'copy')</span>
+<span id="L81" class="LineNr"> 81 </span>  assume-console [
+<span id="L82" class="LineNr"> 82 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 65</span>
+<span id="L83" class="LineNr"> 83 </span>  ]
+<span id="L84" class="LineNr"> 84 </span>  run [
+<span id="L85" class="LineNr"> 85 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L86" class="LineNr"> 86 </span>  ]
+<span id="L87" class="LineNr"> 87 </span>  <span class="Comment"># it pops back into editor</span>
+<span id="L88" class="LineNr"> 88 </span>  screen-should-contain [
+<span id="L89" class="LineNr"> 89 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L90" class="LineNr"> 90 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L91" class="LineNr"> 91 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L92" class="LineNr"> 92 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L93" class="LineNr"> 93 </span>  ]
+<span id="L94" class="LineNr"> 94 </span>  <span class="Comment"># cursor should be in the right place</span>
+<span id="L95" class="LineNr"> 95 </span>  assume-console [
+<span id="L96" class="LineNr"> 96 </span>  <span class="Conceal">¦</span> type <span class="Constant">[0]</span>
+<span id="L97" class="LineNr"> 97 </span>  ]
+<span id="L98" class="LineNr"> 98 </span>  run [
+<span id="L99" class="LineNr"> 99 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L100" class="LineNr">100 </span>  ]
+<span id="L101" class="LineNr">101 </span>  screen-should-contain [
+<span id="L102" class="LineNr">102 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L103" class="LineNr">103 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0add 2, 2                                        .</span>
+<span id="L104" class="LineNr">104 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L105" class="LineNr">105 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L106" class="LineNr">106 </span>  ]
+<span id="L107" class="LineNr">107 </span>]
+<span id="L108" class="LineNr">108 </span>
+<span id="L109" class="LineNr">109 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
+<span id="L110" class="LineNr">110 </span>  <span class="Comment"># support 'edit' button</span>
+<span id="L111" class="LineNr">111 </span>  <span class="Delimiter">{</span>
+<span id="L112" class="LineNr">112 </span>  <span class="Conceal">¦</span> edit?:bool <span class="Special">&lt;-</span> <a href='008-sandbox-edit.mu.html#L123'>should-attempt-edit?</a> click-row, click-column, env
 <span id="L113" class="LineNr">113 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> edit?
-<span id="L114" class="LineNr">114 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L115" class="LineNr">115 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L116" class="LineNr">116 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L117" class="LineNr">117 </span>  <span class="Delimiter">}</span>
-<span id="L118" class="LineNr">118 </span>]
-<span id="L119" class="LineNr">119 </span>
-<span id="L120" class="LineNr">120 </span><span class="Comment"># some preconditions for attempting to edit a sandbox</span>
-<span id="L121" class="LineNr">121 </span><span class="muRecipe">def</span> <a href='008-sandbox-edit.mu.html#L121'>should-attempt-edit?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
-<span id="L122" class="LineNr">122 </span>  <span class="Constant">local-scope</span>
-<span id="L123" class="LineNr">123 </span>  <span class="Constant">load-ingredients</span>
-<span id="L124" class="LineNr">124 </span>  <span class="Comment"># are we below the sandbox editor?</span>
-<span id="L125" class="LineNr">125 </span>  click-sandbox-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L188'>click-on-sandbox-area?</a> click-row, click-column, env
-<span id="L126" class="LineNr">126 </span>  <span class="muControl">return-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
-<span id="L127" class="LineNr">127 </span>  <span class="Comment"># narrower, is the click in the columns spanning the 'edit' button?</span>
-<span id="L128" class="LineNr">128 </span>  first-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L129" class="LineNr">129 </span>  assert first-sandbox, <span class="Constant">[!!]</span>
-<span id="L130" class="LineNr">130 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">left:offset</span>
-<span id="L131" class="LineNr">131 </span>  sandbox-right-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">right:offset</span>
-<span id="L132" class="LineNr">132 </span>  edit-button-left:num, edit-button-right:num, _ <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L340'>sandbox-menu-columns</a> sandbox-left-margin, sandbox-right-margin
-<span id="L133" class="LineNr">133 </span>  edit-button-vertical-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L209'>within-range?</a> click-column, edit-button-left, edit-button-right
-<span id="L134" class="LineNr">134 </span>  <span class="muControl">return-unless</span> edit-button-vertical-area?, <span class="Constant">0/false</span>
-<span id="L135" class="LineNr">135 </span>  <span class="Comment"># finally, is sandbox editor empty?</span>
-<span id="L136" class="LineNr">136 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L137" class="LineNr">137 </span>  result <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L201'>empty-editor?</a> current-sandbox
-<span id="L138" class="LineNr">138 </span>]
-<span id="L139" class="LineNr">139 </span>
-<span id="L140" class="LineNr">140 </span><span class="muRecipe">def</span> <a href='008-sandbox-edit.mu.html#L140'>try-edit-sandbox</a> click-row:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>clicked-on-edit-button?:bool, env:&amp;:environment [
-<span id="L141" class="LineNr">141 </span>  <span class="Constant">local-scope</span>
-<span id="L142" class="LineNr">142 </span>  <span class="Constant">load-ingredients</span>
-<span id="L143" class="LineNr">143 </span>  <span class="Comment"># identify the sandbox to edit, if the click was actually on the 'edit' button</span>
-<span id="L144" class="LineNr">144 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L173'>find-sandbox</a> env, click-row
-<span id="L145" class="LineNr">145 </span>  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
-<span id="L146" class="LineNr">146 </span>  clicked-on-edit-button? <span class="Special">&lt;-</span> copy <span class="Constant">1/true</span>
-<span id="L147" class="LineNr">147 </span>  <span class="Comment"># 'edit' button = 'copy' button + 'delete' button</span>
-<span id="L148" class="LineNr">148 </span>  text:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
-<span id="L149" class="LineNr">149 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
-<span id="L150" class="LineNr">150 </span>  current-sandbox <span class="Special">&lt;-</span> <a href='001-editor.mu.html#L72'>insert-text</a> current-sandbox, text
-<span id="L151" class="LineNr">151 </span>  env <span class="Special">&lt;-</span> <a href='007-sandbox-delete.mu.html#L107'>delete-sandbox</a> env, sandbox
-<span id="L152" class="LineNr">152 </span>  <span class="Comment"># reset scroll</span>
-<span id="L153" class="LineNr">153 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>,<span class="Constant"> -1</span>
-<span id="L154" class="LineNr">154 </span>  <span class="Comment"># position cursor in sandbox editor</span>
-<span id="L155" class="LineNr">155 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox-in-focus?:offset</span>, <span class="Constant">1/true</span>
-<span id="L156" class="LineNr">156 </span>]
-<span id="L157" class="LineNr">157 </span>
-<span id="L158" class="LineNr">158 </span><span class="muScenario">scenario</span> sandbox-with-print-can-be-edited [
-<span id="L159" class="LineNr">159 </span>  <span class="Constant">local-scope</span>
-<span id="L160" class="LineNr">160 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L161" class="LineNr">161 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">20/height</span>
-<span id="L162" class="LineNr">162 </span>  <span class="Comment"># left editor is empty</span>
-<span id="L163" class="LineNr">163 </span>  assume-resources [
-<span id="L164" class="LineNr">164 </span>  ]
-<span id="L165" class="LineNr">165 </span>  <span class="Comment"># right editor contains a print instruction</span>
-<span id="L166" class="LineNr">166 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[print <a href='../081print.mu.html#L4'>screen</a>, 4]</span>
-<span id="L167" class="LineNr">167 </span>  <span class="Comment"># run the sandbox</span>
-<span id="L168" class="LineNr">168 </span>  assume-console [
-<span id="L169" class="LineNr">169 </span>  <span class="Conceal">¦</span> press F4
-<span id="L170" class="LineNr">170 </span>  ]
-<span id="L171" class="LineNr">171 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L172" class="LineNr">172 </span>  screen-should-contain [
-<span id="L173" class="LineNr">173 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L174" class="LineNr">174 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L175" class="LineNr">175 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L176" class="LineNr">176 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L177" class="LineNr">177 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎print <a href='../081print.mu.html#L4'>screen</a>, 4                                  .</span>
-<span id="L178" class="LineNr">178 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎screen:                                          .</span>
-<span id="L179" class="LineNr">179 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .4                             .               .</span>
-<span id="L180" class="LineNr">180 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
-<span id="L181" class="LineNr">181 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
-<span id="L182" class="LineNr">182 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
+<span id="L114" class="LineNr">114 </span>  <span class="Conceal">¦</span> edit?, env <span class="Special">&lt;-</span> <a href='008-sandbox-edit.mu.html#L142'>try-edit-sandbox</a> click-row, env
+<span id="L115" class="LineNr">115 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> edit?
+<span id="L116" class="LineNr">116 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L117" class="LineNr">117 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L118" class="LineNr">118 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L119" class="LineNr">119 </span>  <span class="Delimiter">}</span>
+<span id="L120" class="LineNr">120 </span>]
+<span id="L121" class="LineNr">121 </span>
+<span id="L122" class="LineNr">122 </span><span class="Comment"># some preconditions for attempting to edit a sandbox</span>
+<span id="L123" class="LineNr">123 </span><span class="muRecipe">def</span> <a href='008-sandbox-edit.mu.html#L123'>should-attempt-edit?</a> click-row:num, click-column:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>result:bool [
+<span id="L124" class="LineNr">124 </span>  <span class="Constant">local-scope</span>
+<span id="L125" class="LineNr">125 </span>  <span class="Constant">load-ingredients</span>
+<span id="L126" class="LineNr">126 </span>  <span class="Comment"># are we below the sandbox editor?</span>
+<span id="L127" class="LineNr">127 </span>  click-sandbox-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L190'>click-on-sandbox-area?</a> click-row, click-column, env
+<span id="L128" class="LineNr">128 </span>  <span class="muControl">return-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
+<span id="L129" class="LineNr">129 </span>  <span class="Comment"># narrower, is the click in the columns spanning the 'edit' button?</span>
+<span id="L130" class="LineNr">130 </span>  first-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L131" class="LineNr">131 </span>  assert first-sandbox, <span class="Constant">[!!]</span>
+<span id="L132" class="LineNr">132 </span>  sandbox-left-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">left:offset</span>
+<span id="L133" class="LineNr">133 </span>  sandbox-right-margin:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">right:offset</span>
+<span id="L134" class="LineNr">134 </span>  edit-button-left:num, edit-button-right:num, _ <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L346'>sandbox-menu-columns</a> sandbox-left-margin, sandbox-right-margin
+<span id="L135" class="LineNr">135 </span>  edit-button-vertical-area?:bool <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L211'>within-range?</a> click-column, edit-button-left, edit-button-right
+<span id="L136" class="LineNr">136 </span>  <span class="muControl">return-unless</span> edit-button-vertical-area?, <span class="Constant">0/false</span>
+<span id="L137" class="LineNr">137 </span>  <span class="Comment"># finally, is sandbox editor empty?</span>
+<span id="L138" class="LineNr">138 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L139" class="LineNr">139 </span>  result <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L203'>empty-editor?</a> current-sandbox
+<span id="L140" class="LineNr">140 </span>]
+<span id="L141" class="LineNr">141 </span>
+<span id="L142" class="LineNr">142 </span><span class="muRecipe">def</span> <a href='008-sandbox-edit.mu.html#L142'>try-edit-sandbox</a> click-row:num, env:&amp;:environment<span class="muRecipe"> -&gt; </span>clicked-on-edit-button?:bool, env:&amp;:environment [
+<span id="L143" class="LineNr">143 </span>  <span class="Constant">local-scope</span>
+<span id="L144" class="LineNr">144 </span>  <span class="Constant">load-ingredients</span>
+<span id="L145" class="LineNr">145 </span>  <span class="Comment"># identify the sandbox to edit, if the click was actually on the 'edit' button</span>
+<span id="L146" class="LineNr">146 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='006-sandbox-copy.mu.html#L175'>find-sandbox</a> env, click-row
+<span id="L147" class="LineNr">147 </span>  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
+<span id="L148" class="LineNr">148 </span>  clicked-on-edit-button? <span class="Special">&lt;-</span> copy <span class="Constant">1/true</span>
+<span id="L149" class="LineNr">149 </span>  <span class="Comment"># 'edit' button = 'copy' button + 'delete' button</span>
+<span id="L150" class="LineNr">150 </span>  text:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
+<span id="L151" class="LineNr">151 </span>  current-sandbox:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">current-sandbox:offset</span>
+<span id="L152" class="LineNr">152 </span>  current-sandbox <span class="Special">&lt;-</span> <a href='001-editor.mu.html#L72'>insert-text</a> current-sandbox, text
+<span id="L153" class="LineNr">153 </span>  env <span class="Special">&lt;-</span> <a href='007-sandbox-delete.mu.html#L108'>delete-sandbox</a> env, sandbox
+<span id="L154" class="LineNr">154 </span>  <span class="Comment"># reset scroll</span>
+<span id="L155" class="LineNr">155 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">render-from:offset</span>,<span class="Constant"> -1</span>
+<span id="L156" class="LineNr">156 </span>  <span class="Comment"># position cursor in sandbox editor</span>
+<span id="L157" class="LineNr">157 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">sandbox-in-focus?:offset</span>, <span class="Constant">1/true</span>
+<span id="L158" class="LineNr">158 </span>]
+<span id="L159" class="LineNr">159 </span>
+<span id="L160" class="LineNr">160 </span><span class="muScenario">scenario</span> sandbox-with-print-can-be-edited [
+<span id="L161" class="LineNr">161 </span>  <span class="Constant">local-scope</span>
+<span id="L162" class="LineNr">162 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L163" class="LineNr">163 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">20/height</span>
+<span id="L164" class="LineNr">164 </span>  <span class="Comment"># left editor is empty</span>
+<span id="L165" class="LineNr">165 </span>  assume-resources [
+<span id="L166" class="LineNr">166 </span>  ]
+<span id="L167" class="LineNr">167 </span>  <span class="Comment"># right editor contains a print instruction</span>
+<span id="L168" class="LineNr">168 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[print <a href='../081print.mu.html#L4'>screen</a>, 4]</span>
+<span id="L169" class="LineNr">169 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L170" class="LineNr">170 </span>  <span class="Comment"># run the sandbox</span>
+<span id="L171" class="LineNr">171 </span>  assume-console [
+<span id="L172" class="LineNr">172 </span>  <span class="Conceal">¦</span> press F4
+<span id="L173" class="LineNr">173 </span>  ]
+<span id="L174" class="LineNr">174 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L175" class="LineNr">175 </span>  screen-should-contain [
+<span id="L176" class="LineNr">176 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L177" class="LineNr">177 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L178" class="LineNr">178 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L179" class="LineNr">179 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L180" class="LineNr">180 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎print <a href='../081print.mu.html#L4'>screen</a>, 4                                  .</span>
+<span id="L181" class="LineNr">181 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎screen:                                          .</span>
+<span id="L182" class="LineNr">182 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .4                             .               .</span>
 <span id="L183" class="LineNr">183 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
-<span id="L184" class="LineNr">184 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L185" class="LineNr">185 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L186" class="LineNr">186 </span>  ]
-<span id="L187" class="LineNr">187 </span>  <span class="Comment"># edit the sandbox</span>
-<span id="L188" class="LineNr">188 </span>  assume-console [
-<span id="L189" class="LineNr">189 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 65</span>
-<span id="L190" class="LineNr">190 </span>  ]
-<span id="L191" class="LineNr">191 </span>  run [
-<span id="L192" class="LineNr">192 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L184" class="LineNr">184 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
+<span id="L185" class="LineNr">185 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
+<span id="L186" class="LineNr">186 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎  .                              .               .</span>
+<span id="L187" class="LineNr">187 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L188" class="LineNr">188 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L189" class="LineNr">189 </span>  ]
+<span id="L190" class="LineNr">190 </span>  <span class="Comment"># edit the sandbox</span>
+<span id="L191" class="LineNr">191 </span>  assume-console [
+<span id="L192" class="LineNr">192 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 65</span>
 <span id="L193" class="LineNr">193 </span>  ]
-<span id="L194" class="LineNr">194 </span>  screen-should-contain [
-<span id="L195" class="LineNr">195 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L196" class="LineNr">196 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎print <a href='../081print.mu.html#L4'>screen</a>, 4                                  .</span>
-<span id="L197" class="LineNr">197 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L198" class="LineNr">198 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L199" class="LineNr">199 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L200" class="LineNr">200 </span>  ]
-<span id="L201" class="LineNr">201 </span>]
-<span id="L202" class="LineNr">202 </span>
-<span id="L203" class="LineNr">203 </span><span class="muScenario">scenario</span> editing-sandbox-after-scrolling-resets-scroll [
-<span id="L204" class="LineNr">204 </span>  <span class="Constant">local-scope</span>
-<span id="L205" class="LineNr">205 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L206" class="LineNr">206 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L207" class="LineNr">207 </span>  <span class="Comment"># initialize environment</span>
-<span id="L208" class="LineNr">208 </span>  assume-resources [
-<span id="L209" class="LineNr">209 </span>  ]
-<span id="L210" class="LineNr">210 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L211" class="LineNr">211 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L212" class="LineNr">212 </span>  <span class="Comment"># create 2 sandboxes and scroll to second</span>
-<span id="L213" class="LineNr">213 </span>  assume-console [
-<span id="L214" class="LineNr">214 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L215" class="LineNr">215 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L216" class="LineNr">216 </span>  <span class="Conceal">¦</span> press F4
-<span id="L217" class="LineNr">217 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
-<span id="L218" class="LineNr">218 </span>  <span class="Conceal">¦</span> press F4
-<span id="L219" class="LineNr">219 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L220" class="LineNr">220 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L221" class="LineNr">221 </span>  ]
-<span id="L222" class="LineNr">222 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L223" class="LineNr">223 </span>  screen-should-contain [
-<span id="L224" class="LineNr">224 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L225" class="LineNr">225 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L226" class="LineNr">226 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
-<span id="L227" class="LineNr">227 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L228" class="LineNr">228 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L229" class="LineNr">229 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L230" class="LineNr">230 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L231" class="LineNr">231 </span>  ]
-<span id="L232" class="LineNr">232 </span>  <span class="Comment"># edit the second sandbox</span>
-<span id="L233" class="LineNr">233 </span>  assume-console [
-<span id="L234" class="LineNr">234 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 55</span>
-<span id="L235" class="LineNr">235 </span>  ]
-<span id="L236" class="LineNr">236 </span>  run [
-<span id="L237" class="LineNr">237 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L194" class="LineNr">194 </span>  run [
+<span id="L195" class="LineNr">195 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L196" class="LineNr">196 </span>  ]
+<span id="L197" class="LineNr">197 </span>  screen-should-contain [
+<span id="L198" class="LineNr">198 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L199" class="LineNr">199 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎print <a href='../081print.mu.html#L4'>screen</a>, 4                                  .</span>
+<span id="L200" class="LineNr">200 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L201" class="LineNr">201 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L202" class="LineNr">202 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L203" class="LineNr">203 </span>  ]
+<span id="L204" class="LineNr">204 </span>]
+<span id="L205" class="LineNr">205 </span>
+<span id="L206" class="LineNr">206 </span><span class="muScenario">scenario</span> editing-sandbox-after-scrolling-resets-scroll [
+<span id="L207" class="LineNr">207 </span>  <span class="Constant">local-scope</span>
+<span id="L208" class="LineNr">208 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L209" class="LineNr">209 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L210" class="LineNr">210 </span>  <span class="Comment"># initialize environment</span>
+<span id="L211" class="LineNr">211 </span>  assume-resources [
+<span id="L212" class="LineNr">212 </span>  ]
+<span id="L213" class="LineNr">213 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L214" class="LineNr">214 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L215" class="LineNr">215 </span>  <span class="Comment"># create 2 sandboxes and scroll to second</span>
+<span id="L216" class="LineNr">216 </span>  assume-console [
+<span id="L217" class="LineNr">217 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L218" class="LineNr">218 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L219" class="LineNr">219 </span>  <span class="Conceal">¦</span> press F4
+<span id="L220" class="LineNr">220 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
+<span id="L221" class="LineNr">221 </span>  <span class="Conceal">¦</span> press F4
+<span id="L222" class="LineNr">222 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L223" class="LineNr">223 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L224" class="LineNr">224 </span>  ]
+<span id="L225" class="LineNr">225 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L226" class="LineNr">226 </span>  screen-should-contain [
+<span id="L227" class="LineNr">227 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L228" class="LineNr">228 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L229" class="LineNr">229 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
+<span id="L230" class="LineNr">230 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L231" class="LineNr">231 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L232" class="LineNr">232 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L233" class="LineNr">233 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L234" class="LineNr">234 </span>  ]
+<span id="L235" class="LineNr">235 </span>  <span class="Comment"># edit the second sandbox</span>
+<span id="L236" class="LineNr">236 </span>  assume-console [
+<span id="L237" class="LineNr">237 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 55</span>
 <span id="L238" class="LineNr">238 </span>  ]
-<span id="L239" class="LineNr">239 </span>  <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
-<span id="L240" class="LineNr">240 </span>  screen-should-contain [
-<span id="L241" class="LineNr">241 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L242" class="LineNr">242 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L243" class="LineNr">243 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L244" class="LineNr">244 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L245" class="LineNr">245 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L246" class="LineNr">246 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L247" class="LineNr">247 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L248" class="LineNr">248 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L249" class="LineNr">249 </span>  ]
-<span id="L250" class="LineNr">250 </span>]
-<span id="L251" class="LineNr">251 </span>
-<span id="L252" class="LineNr">252 </span><span class="muScenario">scenario</span> editing-sandbox-updates-sandbox-count [
-<span id="L253" class="LineNr">253 </span>  <span class="Constant">local-scope</span>
-<span id="L254" class="LineNr">254 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L255" class="LineNr">255 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L256" class="LineNr">256 </span>  <span class="Comment"># initialize environment</span>
-<span id="L257" class="LineNr">257 </span>  assume-resources [
-<span id="L258" class="LineNr">258 </span>  ]
-<span id="L259" class="LineNr">259 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L260" class="LineNr">260 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L261" class="LineNr">261 </span>  <span class="Comment"># create 2 sandboxes</span>
-<span id="L262" class="LineNr">262 </span>  assume-console [
-<span id="L263" class="LineNr">263 </span>  <span class="Conceal">¦</span> press ctrl-n
-<span id="L264" class="LineNr">264 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L265" class="LineNr">265 </span>  <span class="Conceal">¦</span> press F4
-<span id="L266" class="LineNr">266 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
-<span id="L267" class="LineNr">267 </span>  <span class="Conceal">¦</span> press F4
-<span id="L268" class="LineNr">268 </span>  ]
-<span id="L269" class="LineNr">269 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L270" class="LineNr">270 </span>  screen-should-contain [
-<span id="L271" class="LineNr">271 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L272" class="LineNr">272 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L273" class="LineNr">273 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L274" class="LineNr">274 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L275" class="LineNr">275 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L276" class="LineNr">276 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L277" class="LineNr">277 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L278" class="LineNr">278 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L279" class="LineNr">279 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L280" class="LineNr">280 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L281" class="LineNr">281 </span>  ]
-<span id="L282" class="LineNr">282 </span>  <span class="Comment"># edit the second sandbox, then resave</span>
-<span id="L283" class="LineNr">283 </span>  assume-console [
-<span id="L284" class="LineNr">284 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 60</span>
-<span id="L285" class="LineNr">285 </span>  <span class="Conceal">¦</span> press F4
-<span id="L286" class="LineNr">286 </span>  ]
-<span id="L287" class="LineNr">287 </span>  run [
-<span id="L288" class="LineNr">288 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L239" class="LineNr">239 </span>  run [
+<span id="L240" class="LineNr">240 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L241" class="LineNr">241 </span>  ]
+<span id="L242" class="LineNr">242 </span>  <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
+<span id="L243" class="LineNr">243 </span>  screen-should-contain [
+<span id="L244" class="LineNr">244 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L245" class="LineNr">245 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L246" class="LineNr">246 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L247" class="LineNr">247 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L248" class="LineNr">248 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L249" class="LineNr">249 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L250" class="LineNr">250 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L251" class="LineNr">251 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L252" class="LineNr">252 </span>  ]
+<span id="L253" class="LineNr">253 </span>]
+<span id="L254" class="LineNr">254 </span>
+<span id="L255" class="LineNr">255 </span><span class="muScenario">scenario</span> editing-sandbox-updates-sandbox-count [
+<span id="L256" class="LineNr">256 </span>  <span class="Constant">local-scope</span>
+<span id="L257" class="LineNr">257 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L258" class="LineNr">258 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L259" class="LineNr">259 </span>  <span class="Comment"># initialize environment</span>
+<span id="L260" class="LineNr">260 </span>  assume-resources [
+<span id="L261" class="LineNr">261 </span>  ]
+<span id="L262" class="LineNr">262 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L263" class="LineNr">263 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L264" class="LineNr">264 </span>  <span class="Comment"># create 2 sandboxes</span>
+<span id="L265" class="LineNr">265 </span>  assume-console [
+<span id="L266" class="LineNr">266 </span>  <span class="Conceal">¦</span> press ctrl-n
+<span id="L267" class="LineNr">267 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L268" class="LineNr">268 </span>  <span class="Conceal">¦</span> press F4
+<span id="L269" class="LineNr">269 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 1, 1]</span>
+<span id="L270" class="LineNr">270 </span>  <span class="Conceal">¦</span> press F4
+<span id="L271" class="LineNr">271 </span>  ]
+<span id="L272" class="LineNr">272 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L273" class="LineNr">273 </span>  screen-should-contain [
+<span id="L274" class="LineNr">274 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L275" class="LineNr">275 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L276" class="LineNr">276 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L277" class="LineNr">277 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L278" class="LineNr">278 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L279" class="LineNr">279 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L280" class="LineNr">280 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L281" class="LineNr">281 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L282" class="LineNr">282 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L283" class="LineNr">283 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L284" class="LineNr">284 </span>  ]
+<span id="L285" class="LineNr">285 </span>  <span class="Comment"># edit the second sandbox, then resave</span>
+<span id="L286" class="LineNr">286 </span>  assume-console [
+<span id="L287" class="LineNr">287 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 60</span>
+<span id="L288" class="LineNr">288 </span>  <span class="Conceal">¦</span> press F4
 <span id="L289" class="LineNr">289 </span>  ]
-<span id="L290" class="LineNr">290 </span>  <span class="Comment"># no change in contents</span>
-<span id="L291" class="LineNr">291 </span>  screen-should-contain [
-<span id="L292" class="LineNr">292 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L293" class="LineNr">293 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L294" class="LineNr">294 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L295" class="LineNr">295 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L296" class="LineNr">296 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
-<span id="L297" class="LineNr">297 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
-<span id="L298" class="LineNr">298 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L299" class="LineNr">299 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
-<span id="L300" class="LineNr">300 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L301" class="LineNr">301 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L302" class="LineNr">302 </span>  ]
-<span id="L303" class="LineNr">303 </span>  <span class="Comment"># now try to scroll past end</span>
-<span id="L304" class="LineNr">304 </span>  assume-console [
-<span id="L305" class="LineNr">305 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L306" class="LineNr">306 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L307" class="LineNr">307 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
-<span id="L308" class="LineNr">308 </span>  ]
-<span id="L309" class="LineNr">309 </span>  run [
-<span id="L310" class="LineNr">310 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L290" class="LineNr">290 </span>  run [
+<span id="L291" class="LineNr">291 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L292" class="LineNr">292 </span>  ]
+<span id="L293" class="LineNr">293 </span>  <span class="Comment"># no change in contents</span>
+<span id="L294" class="LineNr">294 </span>  screen-should-contain [
+<span id="L295" class="LineNr">295 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L296" class="LineNr">296 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L297" class="LineNr">297 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L298" class="LineNr">298 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L299" class="LineNr">299 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 1, 1                                         .</span>
+<span id="L300" class="LineNr">300 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎2                                                .</span>
+<span id="L301" class="LineNr">301 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L302" class="LineNr">302 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎1   edit       copy       to recipe    delete    .</span>
+<span id="L303" class="LineNr">303 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L304" class="LineNr">304 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L305" class="LineNr">305 </span>  ]
+<span id="L306" class="LineNr">306 </span>  <span class="Comment"># now try to scroll past end</span>
+<span id="L307" class="LineNr">307 </span>  assume-console [
+<span id="L308" class="LineNr">308 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L309" class="LineNr">309 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
+<span id="L310" class="LineNr">310 </span>  <span class="Conceal">¦</span> press <a href='003-shortcuts.mu.html#L2981'>page-down</a>
 <span id="L311" class="LineNr">311 </span>  ]
-<span id="L312" class="LineNr">312 </span>  <span class="Comment"># screen should show just final sandbox with the right index (1)</span>
-<span id="L313" class="LineNr">313 </span>  screen-should-contain [
-<span id="L314" class="LineNr">314 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L315" class="LineNr">315 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L316" class="LineNr">316 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
-<span id="L317" class="LineNr">317 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L318" class="LineNr">318 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L319" class="LineNr">319 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L320" class="LineNr">320 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L321" class="LineNr">321 </span>  ]
-<span id="L322" class="LineNr">322 </span>]
+<span id="L312" class="LineNr">312 </span>  run [
+<span id="L313" class="LineNr">313 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L314" class="LineNr">314 </span>  ]
+<span id="L315" class="LineNr">315 </span>  <span class="Comment"># screen should show just final sandbox with the right index (1)</span>
+<span id="L316" class="LineNr">316 </span>  screen-should-contain [
+<span id="L317" class="LineNr">317 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L318" class="LineNr">318 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L319" class="LineNr">319 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎1   edit       copy       to recipe    delete    .</span>
+<span id="L320" class="LineNr">320 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L321" class="LineNr">321 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L322" class="LineNr">322 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L323" class="LineNr">323 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L324" class="LineNr">324 </span>  ]
+<span id="L325" class="LineNr">325 </span>]
 </pre>
 </body>
 </html>
diff --git a/html/edit/009-sandbox-test.mu.html b/html/edit/009-sandbox-test.mu.html
index ead5ff9d..19438380 100644
--- a/html/edit/009-sandbox-test.mu.html
+++ b/html/edit/009-sandbox-test.mu.html
@@ -76,195 +76,196 @@ if ('onhashchange' in window) {
 <span id="L13" class="LineNr"> 13 </span>  <span class="Conceal">¦</span> ]
 <span id="L14" class="LineNr"> 14 </span>  ]
 <span id="L15" class="LineNr"> 15 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
-<span id="L16" class="LineNr"> 16 </span>  <span class="Comment"># run it</span>
-<span id="L17" class="LineNr"> 17 </span>  assume-console [
-<span id="L18" class="LineNr"> 18 </span>  <span class="Conceal">¦</span> press F4
-<span id="L19" class="LineNr"> 19 </span>  ]
-<span id="L20" class="LineNr"> 20 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L21" class="LineNr"> 21 </span>  screen-should-contain [
-<span id="L22" class="LineNr"> 22 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L23" class="LineNr"> 23 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
-<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply 4                                         ╎─────────────────────────────────────────────────.</span>
-<span id="L25" class="LineNr"> 25 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L26" class="LineNr"> 26 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
-<span id="L27" class="LineNr"> 27 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎4                                                .</span>
-<span id="L28" class="LineNr"> 28 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L29" class="LineNr"> 29 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L30" class="LineNr"> 30 </span>  ]
-<span id="L31" class="LineNr"> 31 </span>  <span class="Comment"># click on the '4' in the result</span>
-<span id="L32" class="LineNr"> 32 </span>  assume-console [
-<span id="L33" class="LineNr"> 33 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 5</span>,<span class="Constant"> 51</span>
-<span id="L34" class="LineNr"> 34 </span>  ]
-<span id="L35" class="LineNr"> 35 </span>  run [
-<span id="L36" class="LineNr"> 36 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L37" class="LineNr"> 37 </span>  ]
-<span id="L38" class="LineNr"> 38 </span>  <span class="Comment"># color toggles to green</span>
-<span id="L39" class="LineNr"> 39 </span>  screen-should-contain-in-color <span class="Constant">2/green</span>, [
-<span id="L40" class="LineNr"> 40 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L16" class="LineNr"> 16 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L17" class="LineNr"> 17 </span>  <span class="Comment"># run it</span>
+<span id="L18" class="LineNr"> 18 </span>  assume-console [
+<span id="L19" class="LineNr"> 19 </span>  <span class="Conceal">¦</span> press F4
+<span id="L20" class="LineNr"> 20 </span>  ]
+<span id="L21" class="LineNr"> 21 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L22" class="LineNr"> 22 </span>  screen-should-contain [
+<span id="L23" class="LineNr"> 23 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
+<span id="L25" class="LineNr"> 25 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply 4                                         ╎─────────────────────────────────────────────────.</span>
+<span id="L26" class="LineNr"> 26 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L27" class="LineNr"> 27 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
+<span id="L28" class="LineNr"> 28 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎4                                                .</span>
+<span id="L29" class="LineNr"> 29 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L30" class="LineNr"> 30 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L31" class="LineNr"> 31 </span>  ]
+<span id="L32" class="LineNr"> 32 </span>  <span class="Comment"># click on the '4' in the result</span>
+<span id="L33" class="LineNr"> 33 </span>  assume-console [
+<span id="L34" class="LineNr"> 34 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 5</span>,<span class="Constant"> 51</span>
+<span id="L35" class="LineNr"> 35 </span>  ]
+<span id="L36" class="LineNr"> 36 </span>  run [
+<span id="L37" class="LineNr"> 37 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L38" class="LineNr"> 38 </span>  ]
+<span id="L39" class="LineNr"> 39 </span>  <span class="Comment"># color toggles to green</span>
+<span id="L40" class="LineNr"> 40 </span>  screen-should-contain-in-color <span class="Constant">2/green</span>, [
 <span id="L41" class="LineNr"> 41 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L42" class="LineNr"> 42 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L43" class="LineNr"> 43 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L44" class="LineNr"> 44 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L45" class="LineNr"> 45 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   4                                                .</span>
-<span id="L46" class="LineNr"> 46 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L45" class="LineNr"> 45 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L46" class="LineNr"> 46 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   4                                                .</span>
 <span id="L47" class="LineNr"> 47 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L48" class="LineNr"> 48 </span>  ]
-<span id="L49" class="LineNr"> 49 </span>  <span class="Comment"># cursor should remain unmoved</span>
-<span id="L50" class="LineNr"> 50 </span>  run [
-<span id="L51" class="LineNr"> 51 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L52" class="LineNr"> 52 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L53" class="LineNr"> 53 </span>  ]
-<span id="L54" class="LineNr"> 54 </span>  screen-should-contain [
-<span id="L55" class="LineNr"> 55 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L56" class="LineNr"> 56 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣ecipe foo [                                      ╎                                                 .</span>
-<span id="L57" class="LineNr"> 57 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply 4                                         ╎─────────────────────────────────────────────────.</span>
-<span id="L58" class="LineNr"> 58 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L59" class="LineNr"> 59 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
-<span id="L60" class="LineNr"> 60 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎4                                                .</span>
-<span id="L61" class="LineNr"> 61 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L62" class="LineNr"> 62 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L63" class="LineNr"> 63 </span>  ]
-<span id="L64" class="LineNr"> 64 </span>  <span class="Comment"># now change the result</span>
-<span id="L65" class="LineNr"> 65 </span>  <span class="Comment"># then rerun</span>
-<span id="L66" class="LineNr"> 66 </span>  assume-console [
-<span id="L67" class="LineNr"> 67 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 11</span>  <span class="Comment"># cursor to end of line</span>
-<span id="L68" class="LineNr"> 68 </span>  <span class="Conceal">¦</span> press backspace
-<span id="L69" class="LineNr"> 69 </span>  <span class="Conceal">¦</span> type <span class="Constant">[3]</span>
-<span id="L70" class="LineNr"> 70 </span>  <span class="Conceal">¦</span> press F4
-<span id="L71" class="LineNr"> 71 </span>  ]
-<span id="L72" class="LineNr"> 72 </span>  run [
-<span id="L73" class="LineNr"> 73 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L74" class="LineNr"> 74 </span>  ]
-<span id="L75" class="LineNr"> 75 </span>  <span class="Comment"># result turns red</span>
-<span id="L76" class="LineNr"> 76 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
-<span id="L77" class="LineNr"> 77 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L48" class="LineNr"> 48 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L49" class="LineNr"> 49 </span>  ]
+<span id="L50" class="LineNr"> 50 </span>  <span class="Comment"># cursor should remain unmoved</span>
+<span id="L51" class="LineNr"> 51 </span>  run [
+<span id="L52" class="LineNr"> 52 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L53" class="LineNr"> 53 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
+<span id="L54" class="LineNr"> 54 </span>  ]
+<span id="L55" class="LineNr"> 55 </span>  screen-should-contain [
+<span id="L56" class="LineNr"> 56 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L57" class="LineNr"> 57 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣ecipe foo [                                      ╎                                                 .</span>
+<span id="L58" class="LineNr"> 58 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply 4                                         ╎─────────────────────────────────────────────────.</span>
+<span id="L59" class="LineNr"> 59 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L60" class="LineNr"> 60 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
+<span id="L61" class="LineNr"> 61 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎4                                                .</span>
+<span id="L62" class="LineNr"> 62 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L63" class="LineNr"> 63 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L64" class="LineNr"> 64 </span>  ]
+<span id="L65" class="LineNr"> 65 </span>  <span class="Comment"># now change the result</span>
+<span id="L66" class="LineNr"> 66 </span>  <span class="Comment"># then rerun</span>
+<span id="L67" class="LineNr"> 67 </span>  assume-console [
+<span id="L68" class="LineNr"> 68 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 2</span>,<span class="Constant"> 11</span>  <span class="Comment"># cursor to end of line</span>
+<span id="L69" class="LineNr"> 69 </span>  <span class="Conceal">¦</span> press backspace
+<span id="L70" class="LineNr"> 70 </span>  <span class="Conceal">¦</span> type <span class="Constant">[3]</span>
+<span id="L71" class="LineNr"> 71 </span>  <span class="Conceal">¦</span> press F4
+<span id="L72" class="LineNr"> 72 </span>  ]
+<span id="L73" class="LineNr"> 73 </span>  run [
+<span id="L74" class="LineNr"> 74 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L75" class="LineNr"> 75 </span>  ]
+<span id="L76" class="LineNr"> 76 </span>  <span class="Comment"># result turns red</span>
+<span id="L77" class="LineNr"> 77 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
 <span id="L78" class="LineNr"> 78 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L79" class="LineNr"> 79 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L80" class="LineNr"> 80 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L81" class="LineNr"> 81 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L82" class="LineNr"> 82 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   3                                                .</span>
-<span id="L83" class="LineNr"> 83 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L82" class="LineNr"> 82 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L83" class="LineNr"> 83 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   3                                                .</span>
 <span id="L84" class="LineNr"> 84 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L85" class="LineNr"> 85 </span>  ]
-<span id="L86" class="LineNr"> 86 </span>]
-<span id="L87" class="LineNr"> 87 </span>
-<span id="L88" class="LineNr"> 88 </span><span class="Comment"># this requires tracking a couple more things</span>
-<span id="L89" class="LineNr"> 89 </span><span class="muData">container</span> sandbox [
-<span id="L90" class="LineNr"> 90 </span>  response-starting-row-on-screen:num
-<span id="L91" class="LineNr"> 91 </span>  expected-response:text
-<span id="L92" class="LineNr"> 92 </span>]
-<span id="L93" class="LineNr"> 93 </span>
-<span id="L94" class="LineNr"> 94 </span><span class="Comment"># include expected response when saving or restoring a sandbox</span>
-<span id="L95" class="LineNr"> 95 </span><span class="muRecipe">before</span> <span class="Constant"><a href='005-sandbox.mu.html#L233'>&lt;end-save-sandbox&gt;</a></span> [
-<span id="L96" class="LineNr"> 96 </span>  <span class="Delimiter">{</span>
-<span id="L97" class="LineNr"> 97 </span>  <span class="Conceal">¦</span> expected-response:text <span class="Special">&lt;-</span> get *curr, <span class="Constant">expected-response:offset</span>
-<span id="L98" class="LineNr"> 98 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> expected-response
-<span id="L99" class="LineNr"> 99 </span>  <span class="Conceal">¦</span> filename <span class="Special">&lt;-</span> append filename, <span class="Constant">[.out]</span>
-<span id="L100" class="LineNr">100 </span>  <span class="Conceal">¦</span> <a href='../088file.mu.html#L11'>resources</a> <span class="Special">&lt;-</span> <a href='../088file.mu.html#L127'>dump</a> <a href='../088file.mu.html#L11'>resources</a>, filename, expected-response
-<span id="L101" class="LineNr">101 </span>  <span class="Delimiter">}</span>
-<span id="L102" class="LineNr">102 </span>]
-<span id="L103" class="LineNr">103 </span>
-<span id="L104" class="LineNr">104 </span><span class="muRecipe">before</span> <span class="Constant"><a href='005-sandbox.mu.html#L453'>&lt;end-restore-sandbox&gt;</a></span> [
-<span id="L105" class="LineNr">105 </span>  <span class="Delimiter">{</span>
-<span id="L106" class="LineNr">106 </span>  <span class="Conceal">¦</span> filename <span class="Special">&lt;-</span> append filename, <span class="Constant">[.out]</span>
-<span id="L107" class="LineNr">107 </span>  <span class="Conceal">¦</span> contents <span class="Special">&lt;-</span> <a href='../088file.mu.html#L38'>slurp</a> <a href='../088file.mu.html#L11'>resources</a>, filename
-<span id="L108" class="LineNr">108 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> contents
-<span id="L109" class="LineNr">109 </span>  <span class="Conceal">¦</span> *curr <span class="Special">&lt;-</span> put *curr, <span class="Constant">expected-response:offset</span>, contents
-<span id="L110" class="LineNr">110 </span>  <span class="Delimiter">}</span>
-<span id="L111" class="LineNr">111 </span>]
-<span id="L112" class="LineNr">112 </span>
-<span id="L113" class="LineNr">113 </span><span class="Comment"># clicks on sandbox responses save it as 'expected'</span>
-<span id="L114" class="LineNr">114 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
-<span id="L115" class="LineNr">115 </span>  <span class="Comment"># check if it's inside the output of any sandbox</span>
-<span id="L116" class="LineNr">116 </span>  <span class="Delimiter">{</span>
-<span id="L117" class="LineNr">117 </span>  <span class="Conceal">¦</span> sandbox-left-margin:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
-<span id="L118" class="LineNr">118 </span>  <span class="Conceal">¦</span> click-column:num <span class="Special">&lt;-</span> get t, <span class="Constant">column:offset</span>
-<span id="L119" class="LineNr">119 </span>  <span class="Conceal">¦</span> on-sandbox-side?:bool <span class="Special">&lt;-</span> greater-or-equal click-column, sandbox-left-margin
-<span id="L120" class="LineNr">120 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> on-sandbox-side?
-<span id="L121" class="LineNr">121 </span>  <span class="Conceal">¦</span> first-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L122" class="LineNr">122 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> first-sandbox
-<span id="L123" class="LineNr">123 </span>  <span class="Conceal">¦</span> first-sandbox-begins:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-<span id="L124" class="LineNr">124 </span>  <span class="Conceal">¦</span> click-row:num <span class="Special">&lt;-</span> get t, <span class="Constant">row:offset</span>
-<span id="L125" class="LineNr">125 </span>  <span class="Conceal">¦</span> below-sandbox-editor?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, first-sandbox-begins
-<span id="L126" class="LineNr">126 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> below-sandbox-editor?
-<span id="L127" class="LineNr">127 </span>  <span class="Conceal">¦</span> <span class="Comment"># identify the sandbox whose output is being clicked on</span>
-<span id="L128" class="LineNr">128 </span>  <span class="Conceal">¦</span> sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='009-sandbox-test.mu.html#L139'>find-click-in-sandbox-output</a> env, click-row
-<span id="L129" class="LineNr">129 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox
-<span id="L130" class="LineNr">130 </span>  <span class="Conceal">¦</span> <span class="Comment"># toggle its expected-response, and save session</span>
-<span id="L131" class="LineNr">131 </span>  <span class="Conceal">¦</span> sandbox <span class="Special">&lt;-</span> <a href='009-sandbox-test.mu.html#L165'>toggle-expected-response</a> sandbox
-<span id="L132" class="LineNr">132 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L220'>save-sandboxes</a> env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L133" class="LineNr">133 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L134" class="LineNr">134 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L135" class="LineNr">135 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L136" class="LineNr">136 </span>  <span class="Delimiter">}</span>
-<span id="L137" class="LineNr">137 </span>]
-<span id="L138" class="LineNr">138 </span>
-<span id="L139" class="LineNr">139 </span><span class="muRecipe">def</span> <a href='009-sandbox-test.mu.html#L139'>find-click-in-sandbox-output</a> env:&amp;:environment, click-row:num<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox [
-<span id="L140" class="LineNr">140 </span>  <span class="Constant">local-scope</span>
-<span id="L141" class="LineNr">141 </span>  <span class="Constant">load-ingredients</span>
-<span id="L142" class="LineNr">142 </span>  <span class="Comment"># assert click-row &gt;= sandbox.starting-row-on-screen</span>
-<span id="L143" class="LineNr">143 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L144" class="LineNr">144 </span>  start:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-<span id="L145" class="LineNr">145 </span>  clicked-on-sandboxes?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, start
-<span id="L146" class="LineNr">146 </span>  assert clicked-on-sandboxes?, <span class="Constant">[extract-sandbox called on click to sandbox editor]</span>
-<span id="L147" class="LineNr">147 </span>  <span class="Comment"># while click-row &lt; sandbox.next-sandbox.starting-row-on-screen</span>
-<span id="L148" class="LineNr">148 </span>  <span class="Delimiter">{</span>
-<span id="L149" class="LineNr">149 </span>  <span class="Conceal">¦</span> next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">next-sandbox:offset</span>
-<span id="L150" class="LineNr">150 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> next-sandbox
-<span id="L151" class="LineNr">151 </span>  <span class="Conceal">¦</span> next-start:num <span class="Special">&lt;-</span> get *next-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-<span id="L152" class="LineNr">152 </span>  <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> lesser-than click-row, next-start
-<span id="L153" class="LineNr">153 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> found?
-<span id="L154" class="LineNr">154 </span>  <span class="Conceal">¦</span> sandbox <span class="Special">&lt;-</span> copy next-sandbox
-<span id="L155" class="LineNr">155 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L156" class="LineNr">156 </span>  <span class="Delimiter">}</span>
-<span id="L157" class="LineNr">157 </span>  <span class="Comment"># return sandbox if click is in its output region</span>
-<span id="L158" class="LineNr">158 </span>  response-starting-row:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">response-starting-row-on-screen:offset</span>
-<span id="L159" class="LineNr">159 </span>  <span class="muControl">return-unless</span> response-starting-row, <span class="Constant">0/no-click-in-sandbox-output</span>
-<span id="L160" class="LineNr">160 </span>  click-in-response?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, response-starting-row
-<span id="L161" class="LineNr">161 </span>  <span class="muControl">return-unless</span> click-in-response?, <span class="Constant">0/no-click-in-sandbox-output</span>
-<span id="L162" class="LineNr">162 </span>  <span class="muControl">return</span> sandbox
-<span id="L163" class="LineNr">163 </span>]
-<span id="L164" class="LineNr">164 </span>
-<span id="L165" class="LineNr">165 </span><span class="muRecipe">def</span> <a href='009-sandbox-test.mu.html#L165'>toggle-expected-response</a> sandbox:&amp;:sandbox<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox [
-<span id="L166" class="LineNr">166 </span>  <span class="Constant">local-scope</span>
-<span id="L167" class="LineNr">167 </span>  <span class="Constant">load-ingredients</span>
-<span id="L168" class="LineNr">168 </span>  expected-response:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">expected-response:offset</span>
-<span id="L169" class="LineNr">169 </span>  <span class="Delimiter">{</span>
-<span id="L170" class="LineNr">170 </span>  <span class="Conceal">¦</span> <span class="Comment"># if expected-response is set, reset</span>
-<span id="L171" class="LineNr">171 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> expected-response
-<span id="L172" class="LineNr">172 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">expected-response:offset</span>,<span class="Constant"> 0</span>
-<span id="L173" class="LineNr">173 </span>  <span class="Delimiter">}</span>
-<span id="L174" class="LineNr">174 </span>  <span class="Delimiter">{</span>
-<span id="L175" class="LineNr">175 </span>  <span class="Conceal">¦</span> <span class="Comment"># if not, set expected response to the current response</span>
-<span id="L176" class="LineNr">176 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> expected-response
-<span id="L177" class="LineNr">177 </span>  <span class="Conceal">¦</span> response:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">response:offset</span>
-<span id="L178" class="LineNr">178 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">expected-response:offset</span>, response
-<span id="L179" class="LineNr">179 </span>  <span class="Delimiter">}</span>
-<span id="L180" class="LineNr">180 </span>]
-<span id="L181" class="LineNr">181 </span>
-<span id="L182" class="LineNr">182 </span><span class="Comment"># when rendering a sandbox, color it in red/green if expected response exists</span>
-<span id="L183" class="LineNr">183 </span><span class="muRecipe">after</span> <span class="Constant"><a href='005-sandbox.mu.html#L297'>&lt;render-sandbox-response&gt;</a></span> [
-<span id="L184" class="LineNr">184 </span>  <span class="Delimiter">{</span>
-<span id="L185" class="LineNr">185 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-response
-<span id="L186" class="LineNr">186 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response-starting-row-on-screen:offset</span>, row
-<span id="L187" class="LineNr">187 </span>  <span class="Conceal">¦</span> expected-response:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">expected-response:offset</span>
-<span id="L188" class="LineNr">188 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> expected-response  <span class="Comment"># fall-through to print in grey</span>
-<span id="L189" class="LineNr">189 </span>  <span class="Conceal">¦</span> response-is-expected?:bool <span class="Special">&lt;-</span> equal expected-response, sandbox-response
-<span id="L190" class="LineNr">190 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L191" class="LineNr">191 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> response-is-expected?:bool
-<span id="L192" class="LineNr">192 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L360'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-response, left, right, <span class="Constant">1/red</span>, row
-<span id="L193" class="LineNr">193 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L194" class="LineNr">194 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
-<span id="L195" class="LineNr">195 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> response-is-expected?:bool
-<span id="L196" class="LineNr">196 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L360'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-response, left, right, <span class="Constant">2/green</span>, row
-<span id="L197" class="LineNr">197 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
-<span id="L198" class="LineNr">198 </span>  <span class="Conceal">¦</span> <span class="muControl">jump</span> <span class="Constant">+render-sandbox-end</span>
-<span id="L199" class="LineNr">199 </span>  <span class="Delimiter">}</span>
-<span id="L200" class="LineNr">200 </span>]
-<span id="L201" class="LineNr">201 </span>
-<span id="L202" class="LineNr">202 </span><span class="muRecipe">before</span> <span class="Constant"><a href='005-sandbox.mu.html#L311'>&lt;end-render-sandbox-reset-hidden&gt;</a></span> [
-<span id="L203" class="LineNr">203 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response-starting-row-on-screen:offset</span>,<span class="Constant"> 0</span>
-<span id="L204" class="LineNr">204 </span>]
+<span id="L85" class="LineNr"> 85 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L86" class="LineNr"> 86 </span>  ]
+<span id="L87" class="LineNr"> 87 </span>]
+<span id="L88" class="LineNr"> 88 </span>
+<span id="L89" class="LineNr"> 89 </span><span class="Comment"># this requires tracking a couple more things</span>
+<span id="L90" class="LineNr"> 90 </span><span class="muData">container</span> sandbox [
+<span id="L91" class="LineNr"> 91 </span>  response-starting-row-on-screen:num
+<span id="L92" class="LineNr"> 92 </span>  expected-response:text
+<span id="L93" class="LineNr"> 93 </span>]
+<span id="L94" class="LineNr"> 94 </span>
+<span id="L95" class="LineNr"> 95 </span><span class="Comment"># include expected response when saving or restoring a sandbox</span>
+<span id="L96" class="LineNr"> 96 </span><span class="muRecipe">before</span> <span class="Constant"><a href='005-sandbox.mu.html#L239'>&lt;end-save-sandbox&gt;</a></span> [
+<span id="L97" class="LineNr"> 97 </span>  <span class="Delimiter">{</span>
+<span id="L98" class="LineNr"> 98 </span>  <span class="Conceal">¦</span> expected-response:text <span class="Special">&lt;-</span> get *curr, <span class="Constant">expected-response:offset</span>
+<span id="L99" class="LineNr"> 99 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> expected-response
+<span id="L100" class="LineNr">100 </span>  <span class="Conceal">¦</span> filename <span class="Special">&lt;-</span> append filename, <span class="Constant">[.out]</span>
+<span id="L101" class="LineNr">101 </span>  <span class="Conceal">¦</span> <a href='../088file.mu.html#L11'>resources</a> <span class="Special">&lt;-</span> <a href='../088file.mu.html#L127'>dump</a> <a href='../088file.mu.html#L11'>resources</a>, filename, expected-response
+<span id="L102" class="LineNr">102 </span>  <span class="Delimiter">}</span>
+<span id="L103" class="LineNr">103 </span>]
+<span id="L104" class="LineNr">104 </span>
+<span id="L105" class="LineNr">105 </span><span class="muRecipe">before</span> <span class="Constant"><a href='005-sandbox.mu.html#L459'>&lt;end-restore-sandbox&gt;</a></span> [
+<span id="L106" class="LineNr">106 </span>  <span class="Delimiter">{</span>
+<span id="L107" class="LineNr">107 </span>  <span class="Conceal">¦</span> filename <span class="Special">&lt;-</span> append filename, <span class="Constant">[.out]</span>
+<span id="L108" class="LineNr">108 </span>  <span class="Conceal">¦</span> contents <span class="Special">&lt;-</span> <a href='../088file.mu.html#L38'>slurp</a> <a href='../088file.mu.html#L11'>resources</a>, filename
+<span id="L109" class="LineNr">109 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> contents
+<span id="L110" class="LineNr">110 </span>  <span class="Conceal">¦</span> *curr <span class="Special">&lt;-</span> put *curr, <span class="Constant">expected-response:offset</span>, contents
+<span id="L111" class="LineNr">111 </span>  <span class="Delimiter">}</span>
+<span id="L112" class="LineNr">112 </span>]
+<span id="L113" class="LineNr">113 </span>
+<span id="L114" class="LineNr">114 </span><span class="Comment"># clicks on sandbox responses save it as 'expected'</span>
+<span id="L115" class="LineNr">115 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
+<span id="L116" class="LineNr">116 </span>  <span class="Comment"># check if it's inside the output of any sandbox</span>
+<span id="L117" class="LineNr">117 </span>  <span class="Delimiter">{</span>
+<span id="L118" class="LineNr">118 </span>  <span class="Conceal">¦</span> sandbox-left-margin:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
+<span id="L119" class="LineNr">119 </span>  <span class="Conceal">¦</span> click-column:num <span class="Special">&lt;-</span> get t, <span class="Constant">column:offset</span>
+<span id="L120" class="LineNr">120 </span>  <span class="Conceal">¦</span> on-sandbox-side?:bool <span class="Special">&lt;-</span> greater-or-equal click-column, sandbox-left-margin
+<span id="L121" class="LineNr">121 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> on-sandbox-side?
+<span id="L122" class="LineNr">122 </span>  <span class="Conceal">¦</span> first-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L123" class="LineNr">123 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> first-sandbox
+<span id="L124" class="LineNr">124 </span>  <span class="Conceal">¦</span> first-sandbox-begins:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+<span id="L125" class="LineNr">125 </span>  <span class="Conceal">¦</span> click-row:num <span class="Special">&lt;-</span> get t, <span class="Constant">row:offset</span>
+<span id="L126" class="LineNr">126 </span>  <span class="Conceal">¦</span> below-sandbox-editor?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, first-sandbox-begins
+<span id="L127" class="LineNr">127 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> below-sandbox-editor?
+<span id="L128" class="LineNr">128 </span>  <span class="Conceal">¦</span> <span class="Comment"># identify the sandbox whose output is being clicked on</span>
+<span id="L129" class="LineNr">129 </span>  <span class="Conceal">¦</span> sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='009-sandbox-test.mu.html#L140'>find-click-in-sandbox-output</a> env, click-row
+<span id="L130" class="LineNr">130 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox
+<span id="L131" class="LineNr">131 </span>  <span class="Conceal">¦</span> <span class="Comment"># toggle its expected-response, and save session</span>
+<span id="L132" class="LineNr">132 </span>  <span class="Conceal">¦</span> sandbox <span class="Special">&lt;-</span> <a href='009-sandbox-test.mu.html#L166'>toggle-expected-response</a> sandbox
+<span id="L133" class="LineNr">133 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L226'>save-sandboxes</a> env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L134" class="LineNr">134 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L135" class="LineNr">135 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L136" class="LineNr">136 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L137" class="LineNr">137 </span>  <span class="Delimiter">}</span>
+<span id="L138" class="LineNr">138 </span>]
+<span id="L139" class="LineNr">139 </span>
+<span id="L140" class="LineNr">140 </span><span class="muRecipe">def</span> <a href='009-sandbox-test.mu.html#L140'>find-click-in-sandbox-output</a> env:&amp;:environment, click-row:num<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox [
+<span id="L141" class="LineNr">141 </span>  <span class="Constant">local-scope</span>
+<span id="L142" class="LineNr">142 </span>  <span class="Constant">load-ingredients</span>
+<span id="L143" class="LineNr">143 </span>  <span class="Comment"># assert click-row &gt;= sandbox.starting-row-on-screen</span>
+<span id="L144" class="LineNr">144 </span>  sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L145" class="LineNr">145 </span>  start:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+<span id="L146" class="LineNr">146 </span>  clicked-on-sandboxes?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, start
+<span id="L147" class="LineNr">147 </span>  assert clicked-on-sandboxes?, <span class="Constant">[extract-sandbox called on click to sandbox editor]</span>
+<span id="L148" class="LineNr">148 </span>  <span class="Comment"># while click-row &lt; sandbox.next-sandbox.starting-row-on-screen</span>
+<span id="L149" class="LineNr">149 </span>  <span class="Delimiter">{</span>
+<span id="L150" class="LineNr">150 </span>  <span class="Conceal">¦</span> next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">next-sandbox:offset</span>
+<span id="L151" class="LineNr">151 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> next-sandbox
+<span id="L152" class="LineNr">152 </span>  <span class="Conceal">¦</span> next-start:num <span class="Special">&lt;-</span> get *next-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+<span id="L153" class="LineNr">153 </span>  <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> lesser-than click-row, next-start
+<span id="L154" class="LineNr">154 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> found?
+<span id="L155" class="LineNr">155 </span>  <span class="Conceal">¦</span> sandbox <span class="Special">&lt;-</span> copy next-sandbox
+<span id="L156" class="LineNr">156 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L157" class="LineNr">157 </span>  <span class="Delimiter">}</span>
+<span id="L158" class="LineNr">158 </span>  <span class="Comment"># return sandbox if click is in its output region</span>
+<span id="L159" class="LineNr">159 </span>  response-starting-row:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">response-starting-row-on-screen:offset</span>
+<span id="L160" class="LineNr">160 </span>  <span class="muControl">return-unless</span> response-starting-row, <span class="Constant">0/no-click-in-sandbox-output</span>
+<span id="L161" class="LineNr">161 </span>  click-in-response?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, response-starting-row
+<span id="L162" class="LineNr">162 </span>  <span class="muControl">return-unless</span> click-in-response?, <span class="Constant">0/no-click-in-sandbox-output</span>
+<span id="L163" class="LineNr">163 </span>  <span class="muControl">return</span> sandbox
+<span id="L164" class="LineNr">164 </span>]
+<span id="L165" class="LineNr">165 </span>
+<span id="L166" class="LineNr">166 </span><span class="muRecipe">def</span> <a href='009-sandbox-test.mu.html#L166'>toggle-expected-response</a> sandbox:&amp;:sandbox<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox [
+<span id="L167" class="LineNr">167 </span>  <span class="Constant">local-scope</span>
+<span id="L168" class="LineNr">168 </span>  <span class="Constant">load-ingredients</span>
+<span id="L169" class="LineNr">169 </span>  expected-response:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">expected-response:offset</span>
+<span id="L170" class="LineNr">170 </span>  <span class="Delimiter">{</span>
+<span id="L171" class="LineNr">171 </span>  <span class="Conceal">¦</span> <span class="Comment"># if expected-response is set, reset</span>
+<span id="L172" class="LineNr">172 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> expected-response
+<span id="L173" class="LineNr">173 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">expected-response:offset</span>,<span class="Constant"> 0</span>
+<span id="L174" class="LineNr">174 </span>  <span class="Delimiter">}</span>
+<span id="L175" class="LineNr">175 </span>  <span class="Delimiter">{</span>
+<span id="L176" class="LineNr">176 </span>  <span class="Conceal">¦</span> <span class="Comment"># if not, set expected response to the current response</span>
+<span id="L177" class="LineNr">177 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> expected-response
+<span id="L178" class="LineNr">178 </span>  <span class="Conceal">¦</span> response:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">response:offset</span>
+<span id="L179" class="LineNr">179 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">expected-response:offset</span>, response
+<span id="L180" class="LineNr">180 </span>  <span class="Delimiter">}</span>
+<span id="L181" class="LineNr">181 </span>]
+<span id="L182" class="LineNr">182 </span>
+<span id="L183" class="LineNr">183 </span><span class="Comment"># when rendering a sandbox, color it in red/green if expected response exists</span>
+<span id="L184" class="LineNr">184 </span><span class="muRecipe">after</span> <span class="Constant"><a href='005-sandbox.mu.html#L303'>&lt;render-sandbox-response&gt;</a></span> [
+<span id="L185" class="LineNr">185 </span>  <span class="Delimiter">{</span>
+<span id="L186" class="LineNr">186 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-response
+<span id="L187" class="LineNr">187 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response-starting-row-on-screen:offset</span>, row
+<span id="L188" class="LineNr">188 </span>  <span class="Conceal">¦</span> expected-response:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">expected-response:offset</span>
+<span id="L189" class="LineNr">189 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> expected-response  <span class="Comment"># fall-through to print in grey</span>
+<span id="L190" class="LineNr">190 </span>  <span class="Conceal">¦</span> response-is-expected?:bool <span class="Special">&lt;-</span> equal expected-response, sandbox-response
+<span id="L191" class="LineNr">191 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L192" class="LineNr">192 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-if</span> response-is-expected?:bool
+<span id="L193" class="LineNr">193 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L366'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-response, left, right, <span class="Constant">1/red</span>, row
+<span id="L194" class="LineNr">194 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L195" class="LineNr">195 </span>  <span class="Conceal">¦</span> <span class="Delimiter">{</span>
+<span id="L196" class="LineNr">196 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="muControl">break-unless</span> response-is-expected?:bool
+<span id="L197" class="LineNr">197 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L366'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-response, left, right, <span class="Constant">2/green</span>, row
+<span id="L198" class="LineNr">198 </span>  <span class="Conceal">¦</span> <span class="Delimiter">}</span>
+<span id="L199" class="LineNr">199 </span>  <span class="Conceal">¦</span> <span class="muControl">jump</span> <span class="Constant">+render-sandbox-end</span>
+<span id="L200" class="LineNr">200 </span>  <span class="Delimiter">}</span>
+<span id="L201" class="LineNr">201 </span>]
+<span id="L202" class="LineNr">202 </span>
+<span id="L203" class="LineNr">203 </span><span class="muRecipe">before</span> <span class="Constant"><a href='005-sandbox.mu.html#L317'>&lt;end-render-sandbox-reset-hidden&gt;</a></span> [
+<span id="L204" class="LineNr">204 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response-starting-row-on-screen:offset</span>,<span class="Constant"> 0</span>
+<span id="L205" class="LineNr">205 </span>]
 </pre>
 </body>
 </html>
diff --git a/html/edit/010-sandbox-trace.mu.html b/html/edit/010-sandbox-trace.mu.html
index 5fbc5bb2..b58366b2 100644
--- a/html/edit/010-sandbox-trace.mu.html
+++ b/html/edit/010-sandbox-trace.mu.html
@@ -76,241 +76,244 @@ if ('onhashchange' in window) {
 <span id="L13" class="LineNr"> 13 </span>  <span class="Conceal">¦</span> ]
 <span id="L14" class="LineNr"> 14 </span>  ]
 <span id="L15" class="LineNr"> 15 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
-<span id="L16" class="LineNr"> 16 </span>  <span class="Comment"># run it</span>
-<span id="L17" class="LineNr"> 17 </span>  assume-console [
-<span id="L18" class="LineNr"> 18 </span>  <span class="Conceal">¦</span> press F4
-<span id="L19" class="LineNr"> 19 </span>  ]
-<span id="L20" class="LineNr"> 20 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L21" class="LineNr"> 21 </span>  screen-should-contain [
-<span id="L22" class="LineNr"> 22 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L23" class="LineNr"> 23 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
-<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L25" class="LineNr"> 25 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L26" class="LineNr"> 26 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
-<span id="L27" class="LineNr"> 27 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L28" class="LineNr"> 28 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L29" class="LineNr"> 29 </span>  ]
-<span id="L30" class="LineNr"> 30 </span>  <span class="Comment"># click on the code in the sandbox</span>
-<span id="L31" class="LineNr"> 31 </span>  assume-console [
-<span id="L32" class="LineNr"> 32 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 51</span>
-<span id="L33" class="LineNr"> 33 </span>  ]
-<span id="L34" class="LineNr"> 34 </span>  run [
-<span id="L35" class="LineNr"> 35 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L36" class="LineNr"> 36 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
-<span id="L37" class="LineNr"> 37 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L38" class="LineNr"> 38 </span>  ]
-<span id="L39" class="LineNr"> 39 </span>  <span class="Comment"># trace now printed and cursor shouldn't have budged</span>
-<span id="L40" class="LineNr"> 40 </span>  screen-should-contain [
-<span id="L41" class="LineNr"> 41 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L42" class="LineNr"> 42 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣ecipe foo [                                      ╎                                                 .</span>
-<span id="L43" class="LineNr"> 43 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L44" class="LineNr"> 44 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L45" class="LineNr"> 45 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
-<span id="L46" class="LineNr"> 46 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎abc                                              .</span>
-<span id="L47" class="LineNr"> 47 </span>  ]
-<span id="L48" class="LineNr"> 48 </span>  screen-should-contain-in-color <span class="Constant">245/grey</span>, [
-<span id="L49" class="LineNr"> 49 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L50" class="LineNr"> 50 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L51" class="LineNr"> 51 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L52" class="LineNr"> 52 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L16" class="LineNr"> 16 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L17" class="LineNr"> 17 </span>  <span class="Comment"># run it</span>
+<span id="L18" class="LineNr"> 18 </span>  assume-console [
+<span id="L19" class="LineNr"> 19 </span>  <span class="Conceal">¦</span> press F4
+<span id="L20" class="LineNr"> 20 </span>  ]
+<span id="L21" class="LineNr"> 21 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L22" class="LineNr"> 22 </span>  screen-should-contain [
+<span id="L23" class="LineNr"> 23 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L24" class="LineNr"> 24 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
+<span id="L25" class="LineNr"> 25 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L26" class="LineNr"> 26 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L27" class="LineNr"> 27 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
+<span id="L28" class="LineNr"> 28 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L29" class="LineNr"> 29 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L30" class="LineNr"> 30 </span>  ]
+<span id="L31" class="LineNr"> 31 </span>  <span class="Comment"># click on the code in the sandbox</span>
+<span id="L32" class="LineNr"> 32 </span>  assume-console [
+<span id="L33" class="LineNr"> 33 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 51</span>
+<span id="L34" class="LineNr"> 34 </span>  ]
+<span id="L35" class="LineNr"> 35 </span>  run [
+<span id="L36" class="LineNr"> 36 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L37" class="LineNr"> 37 </span>  <span class="Conceal">¦</span> cursor:char <span class="Special">&lt;-</span> copy <span class="Constant">9251/␣</span>
+<span id="L38" class="LineNr"> 38 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
+<span id="L39" class="LineNr"> 39 </span>  ]
+<span id="L40" class="LineNr"> 40 </span>  <span class="Comment"># trace now printed and cursor shouldn't have budged</span>
+<span id="L41" class="LineNr"> 41 </span>  screen-should-contain [
+<span id="L42" class="LineNr"> 42 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L43" class="LineNr"> 43 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣ecipe foo [                                      ╎                                                 .</span>
+<span id="L44" class="LineNr"> 44 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L45" class="LineNr"> 45 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L46" class="LineNr"> 46 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
+<span id="L47" class="LineNr"> 47 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎abc                                              .</span>
+<span id="L48" class="LineNr"> 48 </span>  ]
+<span id="L49" class="LineNr"> 49 </span>  screen-should-contain-in-color <span class="Constant">245/grey</span>, [
+<span id="L50" class="LineNr"> 50 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L51" class="LineNr"> 51 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L52" class="LineNr"> 52 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
 <span id="L53" class="LineNr"> 53 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L54" class="LineNr"> 54 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎abc                                              .</span>
-<span id="L55" class="LineNr"> 55 </span>  ]
-<span id="L56" class="LineNr"> 56 </span>  <span class="Comment"># click again on the same region</span>
-<span id="L57" class="LineNr"> 57 </span>  assume-console [
-<span id="L58" class="LineNr"> 58 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 55</span>
-<span id="L59" class="LineNr"> 59 </span>  ]
-<span id="L60" class="LineNr"> 60 </span>  run [
-<span id="L61" class="LineNr"> 61 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L62" class="LineNr"> 62 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
-<span id="L63" class="LineNr"> 63 </span>  ]
-<span id="L64" class="LineNr"> 64 </span>  <span class="Comment"># trace hidden again</span>
-<span id="L65" class="LineNr"> 65 </span>  screen-should-contain [
-<span id="L66" class="LineNr"> 66 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L67" class="LineNr"> 67 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣ecipe foo [                                      ╎                                                 .</span>
-<span id="L68" class="LineNr"> 68 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L69" class="LineNr"> 69 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L70" class="LineNr"> 70 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
-<span id="L71" class="LineNr"> 71 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L72" class="LineNr"> 72 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L73" class="LineNr"> 73 </span>  ]
-<span id="L74" class="LineNr"> 74 </span>]
-<span id="L75" class="LineNr"> 75 </span>
-<span id="L76" class="LineNr"> 76 </span><span class="muScenario">scenario</span> sandbox-shows-app-trace-and-result [
-<span id="L77" class="LineNr"> 77 </span>  <span class="Constant">local-scope</span>
-<span id="L78" class="LineNr"> 78 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L79" class="LineNr"> 79 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L80" class="LineNr"> 80 </span>  <span class="Comment"># basic recipe</span>
-<span id="L81" class="LineNr"> 81 </span>  assume-resources [
-<span id="L82" class="LineNr"> 82 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
-<span id="L83" class="LineNr"> 83 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
-<span id="L84" class="LineNr"> 84 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  stash [abc]</span>|
-<span id="L85" class="LineNr"> 85 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|</span>  <span class="muControl">reply</span> 4|
-<span id="L86" class="LineNr"> 86 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]|</span>
-<span id="L87" class="LineNr"> 87 </span>  <span class="Conceal">¦</span> ]
-<span id="L88" class="LineNr"> 88 </span>  ]
-<span id="L89" class="LineNr"> 89 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
-<span id="L90" class="LineNr"> 90 </span>  <span class="Comment"># run it</span>
-<span id="L91" class="LineNr"> 91 </span>  assume-console [
-<span id="L92" class="LineNr"> 92 </span>  <span class="Conceal">¦</span> press F4
-<span id="L93" class="LineNr"> 93 </span>  ]
-<span id="L94" class="LineNr"> 94 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L95" class="LineNr"> 95 </span>  screen-should-contain [
-<span id="L96" class="LineNr"> 96 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L97" class="LineNr"> 97 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
-<span id="L98" class="LineNr"> 98 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L99" class="LineNr"> 99 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply 4                                         ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L100" class="LineNr">100 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎foo                                              .</span>
-<span id="L101" class="LineNr">101 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L102" class="LineNr">102 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L103" class="LineNr">103 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L104" class="LineNr">104 </span>  ]
-<span id="L105" class="LineNr">105 </span>  <span class="Comment"># click on the code in the sandbox</span>
-<span id="L106" class="LineNr">106 </span>  assume-console [
-<span id="L107" class="LineNr">107 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 51</span>
-<span id="L108" class="LineNr">108 </span>  ]
-<span id="L109" class="LineNr">109 </span>  run [
-<span id="L110" class="LineNr">110 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L111" class="LineNr">111 </span>  ]
-<span id="L112" class="LineNr">112 </span>  <span class="Comment"># trace now printed above result</span>
-<span id="L113" class="LineNr">113 </span>  screen-should-contain [
-<span id="L114" class="LineNr">114 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L115" class="LineNr">115 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
-<span id="L116" class="LineNr">116 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L117" class="LineNr">117 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply 4                                         ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L118" class="LineNr">118 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎foo                                              .</span>
-<span id="L119" class="LineNr">119 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎abc                                              .</span>
-<span id="L120" class="LineNr">120 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎8 instructions run                               .</span>
-<span id="L121" class="LineNr">121 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L122" class="LineNr">122 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L123" class="LineNr">123 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L124" class="LineNr">124 </span>  ]
-<span id="L125" class="LineNr">125 </span>]
-<span id="L126" class="LineNr">126 </span>
-<span id="L127" class="LineNr">127 </span><span class="muScenario">scenario</span> clicking-on-app-trace-does-nothing [
-<span id="L128" class="LineNr">128 </span>  <span class="Constant">local-scope</span>
-<span id="L129" class="LineNr">129 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L130" class="LineNr">130 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L131" class="LineNr">131 </span>  assume-resources [
-<span id="L132" class="LineNr">132 </span>  ]
-<span id="L133" class="LineNr">133 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[stash 123456789]</span>
-<span id="L134" class="LineNr">134 </span>  <span class="Comment"># create and expand the trace</span>
-<span id="L135" class="LineNr">135 </span>  assume-console [
-<span id="L136" class="LineNr">136 </span>  <span class="Conceal">¦</span> press F4
-<span id="L137" class="LineNr">137 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 51</span>
-<span id="L138" class="LineNr">138 </span>  ]
-<span id="L139" class="LineNr">139 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L140" class="LineNr">140 </span>  screen-should-contain [
-<span id="L141" class="LineNr">141 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L142" class="LineNr">142 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L143" class="LineNr">143 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L144" class="LineNr">144 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L145" class="LineNr">145 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎stash 123456789                                  .</span>
-<span id="L146" class="LineNr">146 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎123456789                                        .</span>
-<span id="L147" class="LineNr">147 </span>  ]
-<span id="L148" class="LineNr">148 </span>  <span class="Comment"># click on the stash under the edit-button region (or any of the other buttons, really)</span>
-<span id="L149" class="LineNr">149 </span>  assume-console [
-<span id="L150" class="LineNr">150 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 5</span>,<span class="Constant"> 57</span>
-<span id="L151" class="LineNr">151 </span>  ]
-<span id="L152" class="LineNr">152 </span>  run [
-<span id="L153" class="LineNr">153 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L54" class="LineNr"> 54 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L55" class="LineNr"> 55 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎abc                                              .</span>
+<span id="L56" class="LineNr"> 56 </span>  ]
+<span id="L57" class="LineNr"> 57 </span>  <span class="Comment"># click again on the same region</span>
+<span id="L58" class="LineNr"> 58 </span>  assume-console [
+<span id="L59" class="LineNr"> 59 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 55</span>
+<span id="L60" class="LineNr"> 60 </span>  ]
+<span id="L61" class="LineNr"> 61 </span>  run [
+<span id="L62" class="LineNr"> 62 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L63" class="LineNr"> 63 </span>  <span class="Conceal">¦</span> print <a href='../081print.mu.html#L4'>screen</a>, cursor
+<span id="L64" class="LineNr"> 64 </span>  ]
+<span id="L65" class="LineNr"> 65 </span>  <span class="Comment"># trace hidden again</span>
+<span id="L66" class="LineNr"> 66 </span>  screen-should-contain [
+<span id="L67" class="LineNr"> 67 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L68" class="LineNr"> 68 </span>  <span class="Conceal">¦</span><span class="Constant"> .␣ecipe foo [                                      ╎                                                 .</span>
+<span id="L69" class="LineNr"> 69 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L70" class="LineNr"> 70 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L71" class="LineNr"> 71 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎foo                                              .</span>
+<span id="L72" class="LineNr"> 72 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L73" class="LineNr"> 73 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L74" class="LineNr"> 74 </span>  ]
+<span id="L75" class="LineNr"> 75 </span>]
+<span id="L76" class="LineNr"> 76 </span>
+<span id="L77" class="LineNr"> 77 </span><span class="muScenario">scenario</span> sandbox-shows-app-trace-and-result [
+<span id="L78" class="LineNr"> 78 </span>  <span class="Constant">local-scope</span>
+<span id="L79" class="LineNr"> 79 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L80" class="LineNr"> 80 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L81" class="LineNr"> 81 </span>  <span class="Comment"># basic recipe</span>
+<span id="L82" class="LineNr"> 82 </span>  assume-resources [
+<span id="L83" class="LineNr"> 83 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L84" class="LineNr"> 84 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
+<span id="L85" class="LineNr"> 85 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  stash [abc]</span>|
+<span id="L86" class="LineNr"> 86 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|</span>  <span class="muControl">reply</span> 4|
+<span id="L87" class="LineNr"> 87 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]|</span>
+<span id="L88" class="LineNr"> 88 </span>  <span class="Conceal">¦</span> ]
+<span id="L89" class="LineNr"> 89 </span>  ]
+<span id="L90" class="LineNr"> 90 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
+<span id="L91" class="LineNr"> 91 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L92" class="LineNr"> 92 </span>  <span class="Comment"># run it</span>
+<span id="L93" class="LineNr"> 93 </span>  assume-console [
+<span id="L94" class="LineNr"> 94 </span>  <span class="Conceal">¦</span> press F4
+<span id="L95" class="LineNr"> 95 </span>  ]
+<span id="L96" class="LineNr"> 96 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L97" class="LineNr"> 97 </span>  screen-should-contain [
+<span id="L98" class="LineNr"> 98 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L99" class="LineNr"> 99 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
+<span id="L100" class="LineNr">100 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L101" class="LineNr">101 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply 4                                         ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L102" class="LineNr">102 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎foo                                              .</span>
+<span id="L103" class="LineNr">103 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L104" class="LineNr">104 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L105" class="LineNr">105 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L106" class="LineNr">106 </span>  ]
+<span id="L107" class="LineNr">107 </span>  <span class="Comment"># click on the code in the sandbox</span>
+<span id="L108" class="LineNr">108 </span>  assume-console [
+<span id="L109" class="LineNr">109 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 51</span>
+<span id="L110" class="LineNr">110 </span>  ]
+<span id="L111" class="LineNr">111 </span>  run [
+<span id="L112" class="LineNr">112 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L113" class="LineNr">113 </span>  ]
+<span id="L114" class="LineNr">114 </span>  <span class="Comment"># trace now printed above result</span>
+<span id="L115" class="LineNr">115 </span>  screen-should-contain [
+<span id="L116" class="LineNr">116 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L117" class="LineNr">117 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
+<span id="L118" class="LineNr">118 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [abc]                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L119" class="LineNr">119 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply 4                                         ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L120" class="LineNr">120 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎foo                                              .</span>
+<span id="L121" class="LineNr">121 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎abc                                              .</span>
+<span id="L122" class="LineNr">122 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎8 instructions run                               .</span>
+<span id="L123" class="LineNr">123 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L124" class="LineNr">124 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L125" class="LineNr">125 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L126" class="LineNr">126 </span>  ]
+<span id="L127" class="LineNr">127 </span>]
+<span id="L128" class="LineNr">128 </span>
+<span id="L129" class="LineNr">129 </span><span class="muScenario">scenario</span> clicking-on-app-trace-does-nothing [
+<span id="L130" class="LineNr">130 </span>  <span class="Constant">local-scope</span>
+<span id="L131" class="LineNr">131 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L132" class="LineNr">132 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L133" class="LineNr">133 </span>  assume-resources [
+<span id="L134" class="LineNr">134 </span>  ]
+<span id="L135" class="LineNr">135 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[stash 123456789]</span>
+<span id="L136" class="LineNr">136 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L137" class="LineNr">137 </span>  <span class="Comment"># create and expand the trace</span>
+<span id="L138" class="LineNr">138 </span>  assume-console [
+<span id="L139" class="LineNr">139 </span>  <span class="Conceal">¦</span> press F4
+<span id="L140" class="LineNr">140 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 51</span>
+<span id="L141" class="LineNr">141 </span>  ]
+<span id="L142" class="LineNr">142 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L143" class="LineNr">143 </span>  screen-should-contain [
+<span id="L144" class="LineNr">144 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L145" class="LineNr">145 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L146" class="LineNr">146 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L147" class="LineNr">147 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L148" class="LineNr">148 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎stash 123456789                                  .</span>
+<span id="L149" class="LineNr">149 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎123456789                                        .</span>
+<span id="L150" class="LineNr">150 </span>  ]
+<span id="L151" class="LineNr">151 </span>  <span class="Comment"># click on the stash under the edit-button region (or any of the other buttons, really)</span>
+<span id="L152" class="LineNr">152 </span>  assume-console [
+<span id="L153" class="LineNr">153 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 5</span>,<span class="Constant"> 57</span>
 <span id="L154" class="LineNr">154 </span>  ]
-<span id="L155" class="LineNr">155 </span>  <span class="Comment"># no change; doesn't die</span>
-<span id="L156" class="LineNr">156 </span>  screen-should-contain [
-<span id="L157" class="LineNr">157 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L158" class="LineNr">158 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L159" class="LineNr">159 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L160" class="LineNr">160 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L161" class="LineNr">161 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎stash 123456789                                  .</span>
-<span id="L162" class="LineNr">162 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎123456789                                        .</span>
-<span id="L163" class="LineNr">163 </span>  ]
-<span id="L164" class="LineNr">164 </span>]
-<span id="L165" class="LineNr">165 </span>
-<span id="L166" class="LineNr">166 </span><span class="muData">container</span> sandbox [
-<span id="L167" class="LineNr">167 </span>  trace:text
-<span id="L168" class="LineNr">168 </span>  display-trace?:bool
-<span id="L169" class="LineNr">169 </span>]
-<span id="L170" class="LineNr">170 </span>
-<span id="L171" class="LineNr">171 </span><span class="Comment"># replaced in a later layer</span>
-<span id="L172" class="LineNr">172 </span><span class="muRecipe">def!</span> update-sandbox sandbox:&amp;:sandbox, env:&amp;:environment, idx:num<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox, env:&amp;:environment [
-<span id="L173" class="LineNr">173 </span>  <span class="Constant">local-scope</span>
-<span id="L174" class="LineNr">174 </span>  <span class="Constant">load-ingredients</span>
-<span id="L175" class="LineNr">175 </span>  data:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
-<span id="L176" class="LineNr">176 </span>  response:text, _, fake-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a>, trace:text <span class="Special">&lt;-</span> run-sandboxed data
-<span id="L177" class="LineNr">177 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response:offset</span>, response
-<span id="L178" class="LineNr">178 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant"><a href='../081print.mu.html#L4'>screen</a>:offset</span>, fake-screen
-<span id="L179" class="LineNr">179 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">trace:offset</span>, trace
-<span id="L180" class="LineNr">180 </span>]
-<span id="L181" class="LineNr">181 </span>
-<span id="L182" class="LineNr">182 </span><span class="Comment"># clicks on sandbox code toggle its display-trace? flag</span>
-<span id="L183" class="LineNr">183 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
-<span id="L184" class="LineNr">184 </span>  <span class="Comment"># check if it's inside the code of any sandbox</span>
-<span id="L185" class="LineNr">185 </span>  <span class="Delimiter">{</span>
-<span id="L186" class="LineNr">186 </span>  <span class="Conceal">¦</span> sandbox-left-margin:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
-<span id="L187" class="LineNr">187 </span>  <span class="Conceal">¦</span> click-column:num <span class="Special">&lt;-</span> get t, <span class="Constant">column:offset</span>
-<span id="L188" class="LineNr">188 </span>  <span class="Conceal">¦</span> on-sandbox-side?:bool <span class="Special">&lt;-</span> greater-or-equal click-column, sandbox-left-margin
-<span id="L189" class="LineNr">189 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> on-sandbox-side?
-<span id="L190" class="LineNr">190 </span>  <span class="Conceal">¦</span> first-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L191" class="LineNr">191 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> first-sandbox
-<span id="L192" class="LineNr">192 </span>  <span class="Conceal">¦</span> first-sandbox-begins:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-<span id="L193" class="LineNr">193 </span>  <span class="Conceal">¦</span> click-row:num <span class="Special">&lt;-</span> get t, <span class="Constant">row:offset</span>
-<span id="L194" class="LineNr">194 </span>  <span class="Conceal">¦</span> below-sandbox-editor?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, first-sandbox-begins
-<span id="L195" class="LineNr">195 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> below-sandbox-editor?
-<span id="L196" class="LineNr">196 </span>  <span class="Conceal">¦</span> <span class="Comment"># identify the sandbox whose code is being clicked on</span>
-<span id="L197" class="LineNr">197 </span>  <span class="Conceal">¦</span> sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='010-sandbox-trace.mu.html#L209'>find-click-in-sandbox-code</a> env, click-row
-<span id="L198" class="LineNr">198 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox
-<span id="L199" class="LineNr">199 </span>  <span class="Conceal">¦</span> <span class="Comment"># toggle its display-trace? property</span>
-<span id="L200" class="LineNr">200 </span>  <span class="Conceal">¦</span> x:bool <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">display-trace?:offset</span>
-<span id="L201" class="LineNr">201 </span>  <span class="Conceal">¦</span> x <span class="Special">&lt;-</span> not x
-<span id="L202" class="LineNr">202 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">display-trace?:offset</span>, x
-<span id="L203" class="LineNr">203 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L204" class="LineNr">204 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L466'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
-<span id="L205" class="LineNr">205 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
-<span id="L206" class="LineNr">206 </span>  <span class="Delimiter">}</span>
-<span id="L207" class="LineNr">207 </span>]
-<span id="L208" class="LineNr">208 </span>
-<span id="L209" class="LineNr">209 </span><span class="muRecipe">def</span> <a href='010-sandbox-trace.mu.html#L209'>find-click-in-sandbox-code</a> env:&amp;:environment, click-row:num<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox [
-<span id="L210" class="LineNr">210 </span>  <span class="Constant">local-scope</span>
-<span id="L211" class="LineNr">211 </span>  <span class="Constant">load-ingredients</span>
-<span id="L212" class="LineNr">212 </span>  <span class="Comment"># assert click-row &gt;= sandbox.starting-row-on-screen</span>
-<span id="L213" class="LineNr">213 </span>  sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
-<span id="L214" class="LineNr">214 </span>  start:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-<span id="L215" class="LineNr">215 </span>  clicked-on-sandboxes?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, start
-<span id="L216" class="LineNr">216 </span>  assert clicked-on-sandboxes?, <span class="Constant">[extract-sandbox called on click to sandbox editor]</span>
-<span id="L217" class="LineNr">217 </span>  <span class="Comment"># while click-row &lt; sandbox.next-sandbox.starting-row-on-screen</span>
-<span id="L218" class="LineNr">218 </span>  <span class="Delimiter">{</span>
-<span id="L219" class="LineNr">219 </span>  <span class="Conceal">¦</span> next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">next-sandbox:offset</span>
-<span id="L220" class="LineNr">220 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> next-sandbox
-<span id="L221" class="LineNr">221 </span>  <span class="Conceal">¦</span> next-start:num <span class="Special">&lt;-</span> get *next-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-<span id="L222" class="LineNr">222 </span>  <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> lesser-than click-row, next-start
-<span id="L223" class="LineNr">223 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> found?
-<span id="L224" class="LineNr">224 </span>  <span class="Conceal">¦</span> sandbox <span class="Special">&lt;-</span> copy next-sandbox
-<span id="L225" class="LineNr">225 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
-<span id="L226" class="LineNr">226 </span>  <span class="Delimiter">}</span>
-<span id="L227" class="LineNr">227 </span>  <span class="Comment"># return sandbox if click is in its code region</span>
-<span id="L228" class="LineNr">228 </span>  code-ending-row:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">code-ending-row-on-screen:offset</span>
-<span id="L229" class="LineNr">229 </span>  click-above-response?:bool <span class="Special">&lt;-</span> lesser-than click-row, code-ending-row
-<span id="L230" class="LineNr">230 </span>  start:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-<span id="L231" class="LineNr">231 </span>  click-below-menu?:bool <span class="Special">&lt;-</span> greater-than click-row, start
-<span id="L232" class="LineNr">232 </span>  click-on-sandbox-code?:bool <span class="Special">&lt;-</span> and click-above-response?, click-below-menu?
-<span id="L233" class="LineNr">233 </span>  <span class="Delimiter">{</span>
-<span id="L234" class="LineNr">234 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> click-on-sandbox-code?
-<span id="L235" class="LineNr">235 </span>  <span class="Conceal">¦</span> <span class="muControl">return</span> <span class="Constant">0/no-click-in-sandbox-output</span>
-<span id="L236" class="LineNr">236 </span>  <span class="Delimiter">}</span>
-<span id="L237" class="LineNr">237 </span>  <span class="muControl">return</span> sandbox
-<span id="L238" class="LineNr">238 </span>]
-<span id="L239" class="LineNr">239 </span>
-<span id="L240" class="LineNr">240 </span><span class="Comment"># when rendering a sandbox, dump its trace before response/warning if display-trace? property is set</span>
-<span id="L241" class="LineNr">241 </span><span class="muRecipe">after</span> <span class="Constant"><a href='005-sandbox.mu.html#L288'>&lt;render-sandbox-results&gt;</a></span> [
-<span id="L242" class="LineNr">242 </span>  <span class="Delimiter">{</span>
-<span id="L243" class="LineNr">243 </span>  <span class="Conceal">¦</span> display-trace?:bool <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">display-trace?:offset</span>
-<span id="L244" class="LineNr">244 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> display-trace?
-<span id="L245" class="LineNr">245 </span>  <span class="Conceal">¦</span> sandbox-trace:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">trace:offset</span>
-<span id="L246" class="LineNr">246 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-trace  <span class="Comment"># nothing to print; move on</span>
-<span id="L247" class="LineNr">247 </span>  <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L360'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-trace, left, right, <span class="Constant">245/grey</span>, row
-<span id="L248" class="LineNr">248 </span>  <span class="Delimiter">}</span>
-<span id="L249" class="LineNr">249 </span><span class="Constant">  <a href='010-sandbox-trace.mu.html#L249'>&lt;render-sandbox-trace-done&gt;</a></span>
-<span id="L250" class="LineNr">250 </span>]
+<span id="L155" class="LineNr">155 </span>  run [
+<span id="L156" class="LineNr">156 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L157" class="LineNr">157 </span>  ]
+<span id="L158" class="LineNr">158 </span>  <span class="Comment"># no change; doesn't die</span>
+<span id="L159" class="LineNr">159 </span>  screen-should-contain [
+<span id="L160" class="LineNr">160 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L161" class="LineNr">161 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L162" class="LineNr">162 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L163" class="LineNr">163 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L164" class="LineNr">164 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎stash 123456789                                  .</span>
+<span id="L165" class="LineNr">165 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎123456789                                        .</span>
+<span id="L166" class="LineNr">166 </span>  ]
+<span id="L167" class="LineNr">167 </span>]
+<span id="L168" class="LineNr">168 </span>
+<span id="L169" class="LineNr">169 </span><span class="muData">container</span> sandbox [
+<span id="L170" class="LineNr">170 </span>  trace:text
+<span id="L171" class="LineNr">171 </span>  display-trace?:bool
+<span id="L172" class="LineNr">172 </span>]
+<span id="L173" class="LineNr">173 </span>
+<span id="L174" class="LineNr">174 </span><span class="Comment"># replaced in a later layer</span>
+<span id="L175" class="LineNr">175 </span><span class="muRecipe">def!</span> update-sandbox sandbox:&amp;:sandbox, env:&amp;:environment, idx:num<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox, env:&amp;:environment [
+<span id="L176" class="LineNr">176 </span>  <span class="Constant">local-scope</span>
+<span id="L177" class="LineNr">177 </span>  <span class="Constant">load-ingredients</span>
+<span id="L178" class="LineNr">178 </span>  data:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
+<span id="L179" class="LineNr">179 </span>  response:text, _, fake-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a>, trace:text <span class="Special">&lt;-</span> run-sandboxed data
+<span id="L180" class="LineNr">180 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response:offset</span>, response
+<span id="L181" class="LineNr">181 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant"><a href='../081print.mu.html#L4'>screen</a>:offset</span>, fake-screen
+<span id="L182" class="LineNr">182 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">trace:offset</span>, trace
+<span id="L183" class="LineNr">183 </span>]
+<span id="L184" class="LineNr">184 </span>
+<span id="L185" class="LineNr">185 </span><span class="Comment"># clicks on sandbox code toggle its display-trace? flag</span>
+<span id="L186" class="LineNr">186 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L81'>&lt;global-touch&gt;</a></span> [
+<span id="L187" class="LineNr">187 </span>  <span class="Comment"># check if it's inside the code of any sandbox</span>
+<span id="L188" class="LineNr">188 </span>  <span class="Delimiter">{</span>
+<span id="L189" class="LineNr">189 </span>  <span class="Conceal">¦</span> sandbox-left-margin:num <span class="Special">&lt;-</span> get *current-sandbox, <span class="Constant">left:offset</span>
+<span id="L190" class="LineNr">190 </span>  <span class="Conceal">¦</span> click-column:num <span class="Special">&lt;-</span> get t, <span class="Constant">column:offset</span>
+<span id="L191" class="LineNr">191 </span>  <span class="Conceal">¦</span> on-sandbox-side?:bool <span class="Special">&lt;-</span> greater-or-equal click-column, sandbox-left-margin
+<span id="L192" class="LineNr">192 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> on-sandbox-side?
+<span id="L193" class="LineNr">193 </span>  <span class="Conceal">¦</span> first-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L194" class="LineNr">194 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> first-sandbox
+<span id="L195" class="LineNr">195 </span>  <span class="Conceal">¦</span> first-sandbox-begins:num <span class="Special">&lt;-</span> get *first-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+<span id="L196" class="LineNr">196 </span>  <span class="Conceal">¦</span> click-row:num <span class="Special">&lt;-</span> get t, <span class="Constant">row:offset</span>
+<span id="L197" class="LineNr">197 </span>  <span class="Conceal">¦</span> below-sandbox-editor?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, first-sandbox-begins
+<span id="L198" class="LineNr">198 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> below-sandbox-editor?
+<span id="L199" class="LineNr">199 </span>  <span class="Conceal">¦</span> <span class="Comment"># identify the sandbox whose code is being clicked on</span>
+<span id="L200" class="LineNr">200 </span>  <span class="Conceal">¦</span> sandbox:&amp;:sandbox <span class="Special">&lt;-</span> <a href='010-sandbox-trace.mu.html#L212'>find-click-in-sandbox-code</a> env, click-row
+<span id="L201" class="LineNr">201 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox
+<span id="L202" class="LineNr">202 </span>  <span class="Conceal">¦</span> <span class="Comment"># toggle its display-trace? property</span>
+<span id="L203" class="LineNr">203 </span>  <span class="Conceal">¦</span> x:bool <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">display-trace?:offset</span>
+<span id="L204" class="LineNr">204 </span>  <span class="Conceal">¦</span> x <span class="Special">&lt;-</span> not x
+<span id="L205" class="LineNr">205 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">display-trace?:offset</span>, x
+<span id="L206" class="LineNr">206 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> render-sandbox-side <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L207" class="LineNr">207 </span>  <span class="Conceal">¦</span> <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L467'>update-cursor</a> <a href='../081print.mu.html#L4'>screen</a>, recipes, current-sandbox, sandbox-in-focus?, env
+<span id="L208" class="LineNr">208 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span> <span class="Constant">+next-event</span>
+<span id="L209" class="LineNr">209 </span>  <span class="Delimiter">}</span>
+<span id="L210" class="LineNr">210 </span>]
+<span id="L211" class="LineNr">211 </span>
+<span id="L212" class="LineNr">212 </span><span class="muRecipe">def</span> <a href='010-sandbox-trace.mu.html#L212'>find-click-in-sandbox-code</a> env:&amp;:environment, click-row:num<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox [
+<span id="L213" class="LineNr">213 </span>  <span class="Constant">local-scope</span>
+<span id="L214" class="LineNr">214 </span>  <span class="Constant">load-ingredients</span>
+<span id="L215" class="LineNr">215 </span>  <span class="Comment"># assert click-row &gt;= sandbox.starting-row-on-screen</span>
+<span id="L216" class="LineNr">216 </span>  sandbox <span class="Special">&lt;-</span> get *env, <span class="Constant">sandbox:offset</span>
+<span id="L217" class="LineNr">217 </span>  start:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+<span id="L218" class="LineNr">218 </span>  clicked-on-sandboxes?:bool <span class="Special">&lt;-</span> greater-or-equal click-row, start
+<span id="L219" class="LineNr">219 </span>  assert clicked-on-sandboxes?, <span class="Constant">[extract-sandbox called on click to sandbox editor]</span>
+<span id="L220" class="LineNr">220 </span>  <span class="Comment"># while click-row &lt; sandbox.next-sandbox.starting-row-on-screen</span>
+<span id="L221" class="LineNr">221 </span>  <span class="Delimiter">{</span>
+<span id="L222" class="LineNr">222 </span>  <span class="Conceal">¦</span> next-sandbox:&amp;:sandbox <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">next-sandbox:offset</span>
+<span id="L223" class="LineNr">223 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> next-sandbox
+<span id="L224" class="LineNr">224 </span>  <span class="Conceal">¦</span> next-start:num <span class="Special">&lt;-</span> get *next-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+<span id="L225" class="LineNr">225 </span>  <span class="Conceal">¦</span> found?:bool <span class="Special">&lt;-</span> lesser-than click-row, next-start
+<span id="L226" class="LineNr">226 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> found?
+<span id="L227" class="LineNr">227 </span>  <span class="Conceal">¦</span> sandbox <span class="Special">&lt;-</span> copy next-sandbox
+<span id="L228" class="LineNr">228 </span>  <span class="Conceal">¦</span> <span class="muControl">loop</span>
+<span id="L229" class="LineNr">229 </span>  <span class="Delimiter">}</span>
+<span id="L230" class="LineNr">230 </span>  <span class="Comment"># return sandbox if click is in its code region</span>
+<span id="L231" class="LineNr">231 </span>  code-ending-row:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">code-ending-row-on-screen:offset</span>
+<span id="L232" class="LineNr">232 </span>  click-above-response?:bool <span class="Special">&lt;-</span> lesser-than click-row, code-ending-row
+<span id="L233" class="LineNr">233 </span>  start:num <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+<span id="L234" class="LineNr">234 </span>  click-below-menu?:bool <span class="Special">&lt;-</span> greater-than click-row, start
+<span id="L235" class="LineNr">235 </span>  click-on-sandbox-code?:bool <span class="Special">&lt;-</span> and click-above-response?, click-below-menu?
+<span id="L236" class="LineNr">236 </span>  <span class="Delimiter">{</span>
+<span id="L237" class="LineNr">237 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> click-on-sandbox-code?
+<span id="L238" class="LineNr">238 </span>  <span class="Conceal">¦</span> <span class="muControl">return</span> <span class="Constant">0/no-click-in-sandbox-output</span>
+<span id="L239" class="LineNr">239 </span>  <span class="Delimiter">}</span>
+<span id="L240" class="LineNr">240 </span>  <span class="muControl">return</span> sandbox
+<span id="L241" class="LineNr">241 </span>]
+<span id="L242" class="LineNr">242 </span>
+<span id="L243" class="LineNr">243 </span><span class="Comment"># when rendering a sandbox, dump its trace before response/warning if display-trace? property is set</span>
+<span id="L244" class="LineNr">244 </span><span class="muRecipe">after</span> <span class="Constant"><a href='005-sandbox.mu.html#L294'>&lt;render-sandbox-results&gt;</a></span> [
+<span id="L245" class="LineNr">245 </span>  <span class="Delimiter">{</span>
+<span id="L246" class="LineNr">246 </span>  <span class="Conceal">¦</span> display-trace?:bool <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">display-trace?:offset</span>
+<span id="L247" class="LineNr">247 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> display-trace?
+<span id="L248" class="LineNr">248 </span>  <span class="Conceal">¦</span> sandbox-trace:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">trace:offset</span>
+<span id="L249" class="LineNr">249 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-trace  <span class="Comment"># nothing to print; move on</span>
+<span id="L250" class="LineNr">250 </span>  <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L366'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-trace, left, right, <span class="Constant">245/grey</span>, row
+<span id="L251" class="LineNr">251 </span>  <span class="Delimiter">}</span>
+<span id="L252" class="LineNr">252 </span><span class="Constant">  <a href='010-sandbox-trace.mu.html#L252'>&lt;render-sandbox-trace-done&gt;</a></span>
+<span id="L253" class="LineNr">253 </span>]
 </pre>
 </body>
 </html>
diff --git a/html/edit/011-errors.mu.html b/html/edit/011-errors.mu.html
index fa165412..b2a56d31 100644
--- a/html/edit/011-errors.mu.html
+++ b/html/edit/011-errors.mu.html
@@ -72,171 +72,171 @@ if ('onhashchange' in window) {
 <span id="L9" class="LineNr">  9 </span>  <span class="Constant">local-scope</span>
 <span id="L10" class="LineNr"> 10 </span>  <span class="Constant">load-ingredients</span>
 <span id="L11" class="LineNr"> 11 </span>  recipes:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">recipes:offset</span>
-<span id="L12" class="LineNr"> 12 </span>  in:text <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L630'>editor-contents</a> recipes
+<span id="L12" class="LineNr"> 12 </span>  in:text <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L643'>editor-contents</a> recipes
 <span id="L13" class="LineNr"> 13 </span>  <a href='../088file.mu.html#L11'>resources</a> <span class="Special">&lt;-</span> <a href='../088file.mu.html#L127'>dump</a> <a href='../088file.mu.html#L11'>resources</a>, <span class="Constant">[lesson/recipes.mu]</span>, in
 <span id="L14" class="LineNr"> 14 </span>  recipe-errors:text <span class="Special">&lt;-</span> reload in
 <span id="L15" class="LineNr"> 15 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">recipe-errors:offset</span>, recipe-errors
 <span id="L16" class="LineNr"> 16 </span>  <span class="Comment"># if recipe editor has errors, stop</span>
 <span id="L17" class="LineNr"> 17 </span>  <span class="Delimiter">{</span>
 <span id="L18" class="LineNr"> 18 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> recipe-errors
-<span id="L19" class="LineNr"> 19 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L213'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[errors found     ]</span>, <span class="Constant">1/red</span>
+<span id="L19" class="LineNr"> 19 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L219'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[errors found     ]</span>, <span class="Constant">1/red</span>
 <span id="L20" class="LineNr"> 20 </span>  <span class="Conceal">¦</span> errors-found? <span class="Special">&lt;-</span> copy <span class="Constant">1/true</span>
 <span id="L21" class="LineNr"> 21 </span>  <span class="Conceal">¦</span> <span class="muControl">return</span>
 <span id="L22" class="LineNr"> 22 </span>  <span class="Delimiter">}</span>
 <span id="L23" class="LineNr"> 23 </span>  errors-found? <span class="Special">&lt;-</span> copy <span class="Constant">0/false</span>
 <span id="L24" class="LineNr"> 24 </span>]
 <span id="L25" class="LineNr"> 25 </span>
-<span id="L26" class="LineNr"> 26 </span><span class="muRecipe">before</span> <span class="Constant"><a href='004-programming-environment.mu.html#L422'>&lt;render-components-end&gt;</a></span> [
-<span id="L27" class="LineNr"> 27 </span>  trace<span class="Constant"> 11</span>, <span class="Constant">[app]</span>, <span class="Constant">[render status]</span>
-<span id="L28" class="LineNr"> 28 </span>  recipe-errors:text <span class="Special">&lt;-</span> get *env, <span class="Constant">recipe-errors:offset</span>
-<span id="L29" class="LineNr"> 29 </span>  <span class="Delimiter">{</span>
-<span id="L30" class="LineNr"> 30 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> recipe-errors
-<span id="L31" class="LineNr"> 31 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L213'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[errors found     ]</span>, <span class="Constant">1/red</span>
-<span id="L32" class="LineNr"> 32 </span>  <span class="Delimiter">}</span>
-<span id="L33" class="LineNr"> 33 </span>]
-<span id="L34" class="LineNr"> 34 </span>
-<span id="L35" class="LineNr"> 35 </span><span class="muRecipe">before</span> <span class="Constant"><a href='004-programming-environment.mu.html#L443'>&lt;render-recipe-components-end&gt;</a></span> [
-<span id="L36" class="LineNr"> 36 </span>  <span class="Delimiter">{</span>
-<span id="L37" class="LineNr"> 37 </span>  <span class="Conceal">¦</span> recipe-errors:text <span class="Special">&lt;-</span> get *env, <span class="Constant">recipe-errors:offset</span>
-<span id="L38" class="LineNr"> 38 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> recipe-errors
-<span id="L39" class="LineNr"> 39 </span>  <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L360'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, recipe-errors, left, right, <span class="Constant">1/red</span>, row
-<span id="L40" class="LineNr"> 40 </span>  <span class="Delimiter">}</span>
-<span id="L41" class="LineNr"> 41 </span>]
-<span id="L42" class="LineNr"> 42 </span>
-<span id="L43" class="LineNr"> 43 </span><span class="muData">container</span> environment [
-<span id="L44" class="LineNr"> 44 </span>  error-index:num  <span class="Comment"># index of first sandbox with an error (or -1 if none)</span>
-<span id="L45" class="LineNr"> 45 </span>]
-<span id="L46" class="LineNr"> 46 </span>
-<span id="L47" class="LineNr"> 47 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L36'>&lt;programming-environment-initialization&gt;</a></span> [
-<span id="L48" class="LineNr"> 48 </span>  *result <span class="Special">&lt;-</span> put *result, <span class="Constant">error-index:offset</span>,<span class="Constant"> -1</span>
-<span id="L49" class="LineNr"> 49 </span>]
-<span id="L50" class="LineNr"> 50 </span>
-<span id="L51" class="LineNr"> 51 </span><span class="muRecipe">after</span> <span class="Constant"><a href='005-sandbox.mu.html#L149'>&lt;run-sandboxes-begin&gt;</a></span> [
-<span id="L52" class="LineNr"> 52 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">error-index:offset</span>,<span class="Constant"> -1</span>
-<span id="L53" class="LineNr"> 53 </span>]
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-<span id="L55" class="LineNr"> 55 </span><span class="muRecipe">before</span> <span class="Constant"><a href='005-sandbox.mu.html#L183'>&lt;run-sandboxes-end&gt;</a></span> [
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-<span id="L57" class="LineNr"> 57 </span>  <span class="Conceal">¦</span> error-index:num <span class="Special">&lt;-</span> get *env, <span class="Constant">error-index:offset</span>
-<span id="L58" class="LineNr"> 58 </span>  <span class="Conceal">¦</span> sandboxes-completed-successfully?:bool <span class="Special">&lt;-</span> equal error-index,<span class="Constant"> -1</span>
-<span id="L59" class="LineNr"> 59 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> sandboxes-completed-successfully?
-<span id="L60" class="LineNr"> 60 </span>  <span class="Conceal">¦</span> errors-found? <span class="Special">&lt;-</span> copy <span class="Constant">1/true</span>
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-<span id="L66" class="LineNr"> 66 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> recipe-errors
-<span id="L67" class="LineNr"> 67 </span>  <span class="Conceal">¦</span> error-index:num <span class="Special">&lt;-</span> get *env, <span class="Constant">error-index:offset</span>
-<span id="L68" class="LineNr"> 68 </span>  <span class="Conceal">¦</span> sandboxes-completed-successfully?:bool <span class="Special">&lt;-</span> equal error-index,<span class="Constant"> -1</span>
-<span id="L69" class="LineNr"> 69 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> sandboxes-completed-successfully?
-<span id="L70" class="LineNr"> 70 </span>  <span class="Conceal">¦</span> error-index-text:text <span class="Special">&lt;-</span> to-text error-index
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-<span id="L72" class="LineNr"> 72 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L213'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>, status, <span class="Constant">1/red</span>
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-<span id="L75" class="LineNr"> 75 </span>
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-<span id="L84" class="LineNr"> 84 </span>  response:text, errors:text, fake-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a>, trace:text, completed?:bool <span class="Special">&lt;-</span> run-sandboxed data
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-<span id="L86" class="LineNr"> 86 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">errors:offset</span>, errors
-<span id="L87" class="LineNr"> 87 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant"><a href='../081print.mu.html#L4'>screen</a>:offset</span>, fake-screen
-<span id="L88" class="LineNr"> 88 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">trace:offset</span>, trace
-<span id="L89" class="LineNr"> 89 </span>  <span class="Delimiter">{</span>
-<span id="L90" class="LineNr"> 90 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> errors
-<span id="L91" class="LineNr"> 91 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> completed?:bool
-<span id="L92" class="LineNr"> 92 </span>  <span class="Conceal">¦</span> errors <span class="Special">&lt;-</span> new <span class="Constant">[took too long!</span>
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-<span id="L95" class="LineNr"> 95 </span>  <span class="Delimiter">}</span>
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-<span id="L99" class="LineNr"> 99 </span>  <span class="Conceal">¦</span> error-not-set?:bool <span class="Special">&lt;-</span> equal error-index,<span class="Constant"> -1</span>
-<span id="L100" class="LineNr">100 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> error-not-set?
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-<span id="L104" class="LineNr">104 </span>
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-<span id="L107" class="LineNr">107 </span>  <span class="Delimiter">{</span>
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-<span id="L109" class="LineNr">109 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-errors
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-<span id="L111" class="LineNr">111 </span>  <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L360'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-errors, left, right, <span class="Constant">1/red</span>, row
-<span id="L112" class="LineNr">112 </span>  <span class="Conceal">¦</span> <span class="Comment"># don't try to print anything more for this sandbox</span>
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-<span id="L119" class="LineNr">119 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L120" class="LineNr">120 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
-<span id="L121" class="LineNr">121 </span>  assume-resources [
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-<span id="L124" class="LineNr">124 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  get 123:num, foo:offset|</span>
-<span id="L125" class="LineNr">125 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
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-<span id="L129" class="LineNr">129 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
-<span id="L130" class="LineNr">130 </span>  screen-should-contain [
-<span id="L131" class="LineNr">131 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L132" class="LineNr">132 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
-<span id="L133" class="LineNr">133 </span>  <span class="Conceal">¦</span><span class="Constant"> .  get 123:num, foo:offset                         ╎─────────────────────────────────────────────────.</span>
-<span id="L134" class="LineNr">134 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
-<span id="L135" class="LineNr">135 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L136" class="LineNr">136 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L137" class="LineNr">137 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
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-<span id="L139" class="LineNr">139 </span>  assume-console [
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-<span id="L144" class="LineNr">144 </span>  ]
-<span id="L145" class="LineNr">145 </span>  screen-should-contain [
-<span id="L146" class="LineNr">146 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
-<span id="L147" class="LineNr">147 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
-<span id="L148" class="LineNr">148 </span>  <span class="Conceal">¦</span><span class="Constant"> .  get 123:num, foo:offset                         ╎─────────────────────────────────────────────────.</span>
-<span id="L149" class="LineNr">149 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
-<span id="L150" class="LineNr">150 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L151" class="LineNr">151 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: unknown element 'foo' in container 'number'  ╎                                                 .</span>
-<span id="L152" class="LineNr">152 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: first ingredient of 'get' should be a contai↩╎                                                 .</span>
-<span id="L153" class="LineNr">153 </span>  <span class="Conceal">¦</span><span class="Constant"> .ner, but got '123:num'                            ╎                                                 .</span>
-<span id="L154" class="LineNr">154 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L155" class="LineNr">155 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L156" class="LineNr">156 </span>  ]
-<span id="L157" class="LineNr">157 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
-<span id="L158" class="LineNr">158 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                                      .</span>
+<span id="L26" class="LineNr"> 26 </span><span class="muRecipe">after</span> <span class="Constant"><a href='005-sandbox.mu.html#L134'>&lt;render-recipe-errors-on-F4&gt;</a></span> [
+<span id="L27" class="LineNr"> 27 </span>  <span class="Delimiter">{</span>
+<span id="L28" class="LineNr"> 28 </span>  <span class="Conceal">¦</span> recipe-errors:text <span class="Special">&lt;-</span> get *env, <span class="Constant">recipe-errors:offset</span>
+<span id="L29" class="LineNr"> 29 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> recipe-errors
+<span id="L30" class="LineNr"> 30 </span>  <span class="Conceal">¦</span> recipes:&amp;:editor <span class="Special">&lt;-</span> get *env, <span class="Constant">recipes:offset</span>
+<span id="L31" class="LineNr"> 31 </span>  <span class="Conceal">¦</span> left:num <span class="Special">&lt;-</span> get *recipes, <span class="Constant">left:offset</span>
+<span id="L32" class="LineNr"> 32 </span>  <span class="Conceal">¦</span> right:num <span class="Special">&lt;-</span> get *recipes, <span class="Constant">right:offset</span>
+<span id="L33" class="LineNr"> 33 </span>  <span class="Conceal">¦</span> row:num <span class="Special">&lt;-</span> get *env, <span class="Constant">recipe-bottom:offset</span>
+<span id="L34" class="LineNr"> 34 </span>  <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L366'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, recipe-errors, left, right, <span class="Constant">1/red</span>, row
+<span id="L35" class="LineNr"> 35 </span>  <span class="Conceal">¦</span> <span class="Comment"># draw dotted line after recipes</span>
+<span id="L36" class="LineNr"> 36 </span>  <span class="Conceal">¦</span> <a href='002-typing.mu.html#L1060'>draw-horizontal</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, right, <span class="Constant">9480/horizontal-dotted</span>
+<span id="L37" class="LineNr"> 37 </span>  <span class="Conceal">¦</span> row <span class="Special">&lt;-</span> add row,<span class="Constant"> 1</span>
+<span id="L38" class="LineNr"> 38 </span>  <span class="Conceal">¦</span> <a href='001-editor.mu.html#L207'>clear-screen-from</a> <a href='../081print.mu.html#L4'>screen</a>, row, left, left, right
+<span id="L39" class="LineNr"> 39 </span>  <span class="Delimiter">}</span>
+<span id="L40" class="LineNr"> 40 </span>]
+<span id="L41" class="LineNr"> 41 </span>
+<span id="L42" class="LineNr"> 42 </span><span class="muData">container</span> environment [
+<span id="L43" class="LineNr"> 43 </span>  error-index:num  <span class="Comment"># index of first sandbox with an error (or -1 if none)</span>
+<span id="L44" class="LineNr"> 44 </span>]
+<span id="L45" class="LineNr"> 45 </span>
+<span id="L46" class="LineNr"> 46 </span><span class="muRecipe">after</span> <span class="Constant"><a href='004-programming-environment.mu.html#L36'>&lt;programming-environment-initialization&gt;</a></span> [
+<span id="L47" class="LineNr"> 47 </span>  *result <span class="Special">&lt;-</span> put *result, <span class="Constant">error-index:offset</span>,<span class="Constant"> -1</span>
+<span id="L48" class="LineNr"> 48 </span>]
+<span id="L49" class="LineNr"> 49 </span>
+<span id="L50" class="LineNr"> 50 </span><span class="muRecipe">after</span> <span class="Constant"><a href='005-sandbox.mu.html#L155'>&lt;run-sandboxes-begin&gt;</a></span> [
+<span id="L51" class="LineNr"> 51 </span>  *env <span class="Special">&lt;-</span> put *env, <span class="Constant">error-index:offset</span>,<span class="Constant"> -1</span>
+<span id="L52" class="LineNr"> 52 </span>]
+<span id="L53" class="LineNr"> 53 </span>
+<span id="L54" class="LineNr"> 54 </span><span class="muRecipe">before</span> <span class="Constant"><a href='005-sandbox.mu.html#L189'>&lt;run-sandboxes-end&gt;</a></span> [
+<span id="L55" class="LineNr"> 55 </span>  <span class="Delimiter">{</span>
+<span id="L56" class="LineNr"> 56 </span>  <span class="Conceal">¦</span> error-index:num <span class="Special">&lt;-</span> get *env, <span class="Constant">error-index:offset</span>
+<span id="L57" class="LineNr"> 57 </span>  <span class="Conceal">¦</span> sandboxes-completed-successfully?:bool <span class="Special">&lt;-</span> equal error-index,<span class="Constant"> -1</span>
+<span id="L58" class="LineNr"> 58 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> sandboxes-completed-successfully?
+<span id="L59" class="LineNr"> 59 </span>  <span class="Conceal">¦</span> errors-found? <span class="Special">&lt;-</span> copy <span class="Constant">1/true</span>
+<span id="L60" class="LineNr"> 60 </span>  <span class="Delimiter">}</span>
+<span id="L61" class="LineNr"> 61 </span>]
+<span id="L62" class="LineNr"> 62 </span>
+<span id="L63" class="LineNr"> 63 </span><span class="muRecipe">after</span> <span class="Constant"><a href='005-sandbox.mu.html#L142'>&lt;render-sandbox-errors-on-F4&gt;</a></span> [
+<span id="L64" class="LineNr"> 64 </span>  <span class="Delimiter">{</span>
+<span id="L65" class="LineNr"> 65 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> recipe-errors
+<span id="L66" class="LineNr"> 66 </span>  <span class="Conceal">¦</span> error-index:num <span class="Special">&lt;-</span> get *env, <span class="Constant">error-index:offset</span>
+<span id="L67" class="LineNr"> 67 </span>  <span class="Conceal">¦</span> sandboxes-completed-successfully?:bool <span class="Special">&lt;-</span> equal error-index,<span class="Constant"> -1</span>
+<span id="L68" class="LineNr"> 68 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> sandboxes-completed-successfully?
+<span id="L69" class="LineNr"> 69 </span>  <span class="Conceal">¦</span> error-index-text:text <span class="Special">&lt;-</span> to-text error-index
+<span id="L70" class="LineNr"> 70 </span>  <span class="Conceal">¦</span> status:text <span class="Special">&lt;-</span> <a href='../061text.mu.html#L521'>interpolate</a> <span class="Constant">[errors found (_)    ]</span>, error-index-text
+<span id="L71" class="LineNr"> 71 </span>  <span class="Conceal">¦</span> <a href='005-sandbox.mu.html#L219'>update-status</a> <a href='../081print.mu.html#L4'>screen</a>, status, <span class="Constant">1/red</span>
+<span id="L72" class="LineNr"> 72 </span>  <span class="Delimiter">}</span>
+<span id="L73" class="LineNr"> 73 </span>]
+<span id="L74" class="LineNr"> 74 </span>
+<span id="L75" class="LineNr"> 75 </span><span class="muData">container</span> sandbox [
+<span id="L76" class="LineNr"> 76 </span>  errors:text
+<span id="L77" class="LineNr"> 77 </span>]
+<span id="L78" class="LineNr"> 78 </span>
+<span id="L79" class="LineNr"> 79 </span><span class="muRecipe">def!</span> update-sandbox sandbox:&amp;:sandbox, env:&amp;:environment, idx:num<span class="muRecipe"> -&gt; </span>sandbox:&amp;:sandbox, env:&amp;:environment [
+<span id="L80" class="LineNr"> 80 </span>  <span class="Constant">local-scope</span>
+<span id="L81" class="LineNr"> 81 </span>  <span class="Constant">load-ingredients</span>
+<span id="L82" class="LineNr"> 82 </span>  data:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">data:offset</span>
+<span id="L83" class="LineNr"> 83 </span>  response:text, errors:text, fake-screen:&amp;:<a href='../081print.mu.html#L4'>screen</a>, trace:text, completed?:bool <span class="Special">&lt;-</span> run-sandboxed data
+<span id="L84" class="LineNr"> 84 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response:offset</span>, response
+<span id="L85" class="LineNr"> 85 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">errors:offset</span>, errors
+<span id="L86" class="LineNr"> 86 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant"><a href='../081print.mu.html#L4'>screen</a>:offset</span>, fake-screen
+<span id="L87" class="LineNr"> 87 </span>  *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">trace:offset</span>, trace
+<span id="L88" class="LineNr"> 88 </span>  <span class="Delimiter">{</span>
+<span id="L89" class="LineNr"> 89 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> errors
+<span id="L90" class="LineNr"> 90 </span>  <span class="Conceal">¦</span> <span class="muControl">break-if</span> completed?:bool
+<span id="L91" class="LineNr"> 91 </span>  <span class="Conceal">¦</span> errors <span class="Special">&lt;-</span> new <span class="Constant">[took too long!</span>
+<span id="L92" class="LineNr"> 92 </span><span class="Constant">]</span>
+<span id="L93" class="LineNr"> 93 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">errors:offset</span>, errors
+<span id="L94" class="LineNr"> 94 </span>  <span class="Delimiter">}</span>
+<span id="L95" class="LineNr"> 95 </span>  <span class="Delimiter">{</span>
+<span id="L96" class="LineNr"> 96 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> errors
+<span id="L97" class="LineNr"> 97 </span>  <span class="Conceal">¦</span> error-index:num <span class="Special">&lt;-</span> get *env, <span class="Constant">error-index:offset</span>
+<span id="L98" class="LineNr"> 98 </span>  <span class="Conceal">¦</span> error-not-set?:bool <span class="Special">&lt;-</span> equal error-index,<span class="Constant"> -1</span>
+<span id="L99" class="LineNr"> 99 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> error-not-set?
+<span id="L100" class="LineNr">100 </span>  <span class="Conceal">¦</span> *env <span class="Special">&lt;-</span> put *env, <span class="Constant">error-index:offset</span>, idx
+<span id="L101" class="LineNr">101 </span>  <span class="Delimiter">}</span>
+<span id="L102" class="LineNr">102 </span>]
+<span id="L103" class="LineNr">103 </span>
+<span id="L104" class="LineNr">104 </span><span class="Comment"># make sure we render any trace</span>
+<span id="L105" class="LineNr">105 </span><span class="muRecipe">after</span> <span class="Constant"><a href='010-sandbox-trace.mu.html#L252'>&lt;render-sandbox-trace-done&gt;</a></span> [
+<span id="L106" class="LineNr">106 </span>  <span class="Delimiter">{</span>
+<span id="L107" class="LineNr">107 </span>  <span class="Conceal">¦</span> sandbox-errors:text <span class="Special">&lt;-</span> get *sandbox, <span class="Constant">errors:offset</span>
+<span id="L108" class="LineNr">108 </span>  <span class="Conceal">¦</span> <span class="muControl">break-unless</span> sandbox-errors
+<span id="L109" class="LineNr">109 </span>  <span class="Conceal">¦</span> *sandbox <span class="Special">&lt;-</span> put *sandbox, <span class="Constant">response-starting-row-on-screen:offset</span>,<span class="Constant"> 0</span>  <span class="Comment"># no response</span>
+<span id="L110" class="LineNr">110 </span>  <span class="Conceal">¦</span> row, <a href='../081print.mu.html#L4'>screen</a> <span class="Special">&lt;-</span> <a href='005-sandbox.mu.html#L366'>render-text</a> <a href='../081print.mu.html#L4'>screen</a>, sandbox-errors, left, right, <span class="Constant">1/red</span>, row
+<span id="L111" class="LineNr">111 </span>  <span class="Conceal">¦</span> <span class="Comment"># don't try to print anything more for this sandbox</span>
+<span id="L112" class="LineNr">112 </span>  <span class="Conceal">¦</span> <span class="muControl">jump</span> <span class="Constant">+render-sandbox-end</span>
+<span id="L113" class="LineNr">113 </span>  <span class="Delimiter">}</span>
+<span id="L114" class="LineNr">114 </span>]
+<span id="L115" class="LineNr">115 </span>
+<span id="L116" class="LineNr">116 </span><span class="muScenario">scenario</span> run-shows-errors-in-get [
+<span id="L117" class="LineNr">117 </span>  <span class="Constant">local-scope</span>
+<span id="L118" class="LineNr">118 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L119" class="LineNr">119 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
+<span id="L120" class="LineNr">120 </span>  assume-resources [
+<span id="L121" class="LineNr">121 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L122" class="LineNr">122 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
+<span id="L123" class="LineNr">123 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  get 123:num, foo:offset|</span>
+<span id="L124" class="LineNr">124 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
+<span id="L125" class="LineNr">125 </span>  <span class="Conceal">¦</span> ]
+<span id="L126" class="LineNr">126 </span>  ]
+<span id="L127" class="LineNr">127 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
+<span id="L128" class="LineNr">128 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L129" class="LineNr">129 </span>  screen-should-contain [
+<span id="L130" class="LineNr">130 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L131" class="LineNr">131 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
+<span id="L132" class="LineNr">132 </span>  <span class="Conceal">¦</span><span class="Constant"> .  get 123:num, foo:offset                         ╎─────────────────────────────────────────────────.</span>
+<span id="L133" class="LineNr">133 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
+<span id="L134" class="LineNr">134 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L135" class="LineNr">135 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L136" class="LineNr">136 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L137" class="LineNr">137 </span>  ]
+<span id="L138" class="LineNr">138 </span>  assume-console [
+<span id="L139" class="LineNr">139 </span>  <span class="Conceal">¦</span> press F4
+<span id="L140" class="LineNr">140 </span>  ]
+<span id="L141" class="LineNr">141 </span>  run [
+<span id="L142" class="LineNr">142 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L143" class="LineNr">143 </span>  ]
+<span id="L144" class="LineNr">144 </span>  screen-should-contain [
+<span id="L145" class="LineNr">145 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
+<span id="L146" class="LineNr">146 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
+<span id="L147" class="LineNr">147 </span>  <span class="Conceal">¦</span><span class="Constant"> .  get 123:num, foo:offset                         ╎─────────────────────────────────────────────────.</span>
+<span id="L148" class="LineNr">148 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
+<span id="L149" class="LineNr">149 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L150" class="LineNr">150 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: unknown element 'foo' in container 'number'  ╎                                                 .</span>
+<span id="L151" class="LineNr">151 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: first ingredient of 'get' should be a contai↩╎                                                 .</span>
+<span id="L152" class="LineNr">152 </span>  <span class="Conceal">¦</span><span class="Constant"> .ner, but got '123:num'                            ╎                                                 .</span>
+<span id="L153" class="LineNr">153 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L154" class="LineNr">154 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L155" class="LineNr">155 </span>  ]
+<span id="L156" class="LineNr">156 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
+<span id="L157" class="LineNr">157 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                                      .</span>
+<span id="L158" class="LineNr">158 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L159" class="LineNr">159 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L160" class="LineNr">160 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L161" class="LineNr">161 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L162" class="LineNr">162 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L163" class="LineNr">163 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: unknown element 'foo' in container 'number'                                                    .</span>
-<span id="L164" class="LineNr">164 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: first ingredient of 'get' should be a contai                                                   .</span>
-<span id="L165" class="LineNr">165 </span>  <span class="Conceal">¦</span><span class="Constant"> .ner, but got '123:num'                                                                              .</span>
-<span id="L166" class="LineNr">166 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L167" class="LineNr">167 </span>  ]
-<span id="L168" class="LineNr">168 </span>]
-<span id="L169" class="LineNr">169 </span>
-<span id="L170" class="LineNr">170 </span><span class="muScenario">scenario</span> run-updates-status-with-first-erroneous-sandbox [
-<span id="L171" class="LineNr">171 </span>  <span class="Constant">local-scope</span>
-<span id="L172" class="LineNr">172 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L173" class="LineNr">173 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
-<span id="L174" class="LineNr">174 </span>  assume-resources [
-<span id="L175" class="LineNr">175 </span>  ]
-<span id="L176" class="LineNr">176 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L162" class="LineNr">162 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: unknown element 'foo' in container 'number'                                                    .</span>
+<span id="L163" class="LineNr">163 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: first ingredient of 'get' should be a contai                                                   .</span>
+<span id="L164" class="LineNr">164 </span>  <span class="Conceal">¦</span><span class="Constant"> .ner, but got '123:num'                                                                              .</span>
+<span id="L165" class="LineNr">165 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L166" class="LineNr">166 </span>  ]
+<span id="L167" class="LineNr">167 </span>]
+<span id="L168" class="LineNr">168 </span>
+<span id="L169" class="LineNr">169 </span><span class="muScenario">scenario</span> run-updates-status-with-first-erroneous-sandbox [
+<span id="L170" class="LineNr">170 </span>  <span class="Constant">local-scope</span>
+<span id="L171" class="LineNr">171 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L172" class="LineNr">172 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
+<span id="L173" class="LineNr">173 </span>  assume-resources [
+<span id="L174" class="LineNr">174 </span>  ]
+<span id="L175" class="LineNr">175 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
+<span id="L176" class="LineNr">176 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
 <span id="L177" class="LineNr">177 </span>  assume-console [
 <span id="L178" class="LineNr">178 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 80</span>
 <span id="L179" class="LineNr">179 </span>  <span class="Conceal">¦</span> <span class="Comment"># create invalid sandbox 1</span>
@@ -262,547 +262,560 @@ if ('onhashchange' in window) {
 <span id="L199" class="LineNr">199 </span>  assume-resources [
 <span id="L200" class="LineNr">200 </span>  ]
 <span id="L201" class="LineNr">201 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[]</span>
-<span id="L202" class="LineNr">202 </span>  assume-console [
-<span id="L203" class="LineNr">203 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 80</span>
-<span id="L204" class="LineNr">204 </span>  <span class="Conceal">¦</span> <span class="Comment"># create invalid sandbox 2</span>
-<span id="L205" class="LineNr">205 </span>  <span class="Conceal">¦</span> type <span class="Constant">[get foo, x:offset]</span>
-<span id="L206" class="LineNr">206 </span>  <span class="Conceal">¦</span> press F4
-<span id="L207" class="LineNr">207 </span>  <span class="Conceal">¦</span> <span class="Comment"># create invalid sandbox 1</span>
-<span id="L208" class="LineNr">208 </span>  <span class="Conceal">¦</span> type <span class="Constant">[get foo, x:offset]</span>
-<span id="L209" class="LineNr">209 </span>  <span class="Conceal">¦</span> press F4
-<span id="L210" class="LineNr">210 </span>  <span class="Conceal">¦</span> <span class="Comment"># create valid sandbox 0</span>
-<span id="L211" class="LineNr">211 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
-<span id="L212" class="LineNr">212 </span>  <span class="Conceal">¦</span> press F4
-<span id="L213" class="LineNr">213 </span>  ]
-<span id="L214" class="LineNr">214 </span>  run [
-<span id="L215" class="LineNr">215 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L216" class="LineNr">216 </span>  ]
-<span id="L217" class="LineNr">217 </span>  <span class="Comment"># status line shows that error is in second sandbox</span>
-<span id="L218" class="LineNr">218 </span>  screen-should-contain [
-<span id="L219" class="LineNr">219 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (1)                                                               run (F4)           .</span>
-<span id="L220" class="LineNr">220 </span>  ]
-<span id="L221" class="LineNr">221 </span>]
-<span id="L222" class="LineNr">222 </span>
-<span id="L223" class="LineNr">223 </span><span class="muScenario">scenario</span> run-hides-errors-from-past-sandboxes [
-<span id="L224" class="LineNr">224 </span>  <span class="Constant">local-scope</span>
-<span id="L225" class="LineNr">225 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L226" class="LineNr">226 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
-<span id="L227" class="LineNr">227 </span>  assume-resources [
-<span id="L228" class="LineNr">228 </span>  ]
-<span id="L229" class="LineNr">229 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[get foo, x:offset]</span>  <span class="Comment"># invalid</span>
-<span id="L230" class="LineNr">230 </span>  assume-console [
-<span id="L231" class="LineNr">231 </span>  <span class="Conceal">¦</span> press F4  <span class="Comment"># generate error</span>
-<span id="L232" class="LineNr">232 </span>  ]
-<span id="L233" class="LineNr">233 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L234" class="LineNr">234 </span>  assume-console [
-<span id="L235" class="LineNr">235 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 58</span>
-<span id="L236" class="LineNr">236 </span>  <span class="Conceal">¦</span> press ctrl-k
-<span id="L237" class="LineNr">237 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>  <span class="Comment"># valid code</span>
-<span id="L238" class="LineNr">238 </span>  <span class="Conceal">¦</span> press F4  <span class="Comment"># update sandbox</span>
-<span id="L239" class="LineNr">239 </span>  ]
-<span id="L240" class="LineNr">240 </span>  run [
-<span id="L241" class="LineNr">241 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L242" class="LineNr">242 </span>  ]
-<span id="L243" class="LineNr">243 </span>  <span class="Comment"># error should disappear</span>
-<span id="L244" class="LineNr">244 </span>  screen-should-contain [
-<span id="L245" class="LineNr">245 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
-<span id="L246" class="LineNr">246 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L247" class="LineNr">247 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L248" class="LineNr">248 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L249" class="LineNr">249 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
-<span id="L250" class="LineNr">250 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
-<span id="L251" class="LineNr">251 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L252" class="LineNr">252 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L253" class="LineNr">253 </span>  ]
-<span id="L254" class="LineNr">254 </span>]
-<span id="L255" class="LineNr">255 </span>
-<span id="L256" class="LineNr">256 </span><span class="muScenario">scenario</span> run-updates-errors-for-shape-shifting-recipes [
-<span id="L257" class="LineNr">257 </span>  <span class="Constant">local-scope</span>
-<span id="L258" class="LineNr">258 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L259" class="LineNr">259 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
-<span id="L260" class="LineNr">260 </span>  <span class="Comment"># define a shape-shifting recipe with an error</span>
-<span id="L261" class="LineNr">261 </span>  assume-resources [
-<span id="L262" class="LineNr">262 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
-<span id="L263" class="LineNr">263 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo x:_elem<span class="muRecipe"> -&gt; </span>z:_elem <span class="Constant">[|</span>
-<span id="L264" class="LineNr">264 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  local-scope|</span>
-<span id="L265" class="LineNr">265 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  load-ingredients|</span>
-<span id="L266" class="LineNr">266 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  y:&amp;:num &lt;- copy 0|</span>
-<span id="L267" class="LineNr">267 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  z &lt;- add x, y|</span>
-<span id="L268" class="LineNr">268 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
-<span id="L269" class="LineNr">269 </span>  <span class="Conceal">¦</span> ]
-<span id="L270" class="LineNr">270 </span>  ]
-<span id="L271" class="LineNr">271 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo 2]</span>
-<span id="L272" class="LineNr">272 </span>  assume-console [
-<span id="L273" class="LineNr">273 </span>  <span class="Conceal">¦</span> press F4
-<span id="L274" class="LineNr">274 </span>  ]
-<span id="L275" class="LineNr">275 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L276" class="LineNr">276 </span>  screen-should-contain [
-<span id="L277" class="LineNr">277 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
-<span id="L278" class="LineNr">278 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo x:_elem -&gt; z:_elem [                   ╎                                                 .</span>
-<span id="L279" class="LineNr">279 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L280" class="LineNr">280 </span>  <span class="Conceal">¦</span><span class="Constant"> .  load-ingredients                                ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L281" class="LineNr">281 </span>  <span class="Conceal">¦</span><span class="Constant"> .  y:&amp;:num &lt;- copy 0                               ╎foo 2                                            .</span>
-<span id="L282" class="LineNr">282 </span>  <span class="Conceal">¦</span><span class="Constant"> .  z &lt;- add x, y                                   ╎foo_2: 'add' requires number ingredients, but go↩.</span>
-<span id="L283" class="LineNr">283 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎t 'y'                                            .</span>
-<span id="L284" class="LineNr">284 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L285" class="LineNr">285 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L286" class="LineNr">286 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L287" class="LineNr">287 </span>  ]
-<span id="L288" class="LineNr">288 </span>  <span class="Comment"># now rerun everything</span>
-<span id="L289" class="LineNr">289 </span>  assume-console [
-<span id="L290" class="LineNr">290 </span>  <span class="Conceal">¦</span> press F4
-<span id="L291" class="LineNr">291 </span>  ]
-<span id="L292" class="LineNr">292 </span>  run [
-<span id="L293" class="LineNr">293 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L202" class="LineNr">202 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L203" class="LineNr">203 </span>  assume-console [
+<span id="L204" class="LineNr">204 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 80</span>
+<span id="L205" class="LineNr">205 </span>  <span class="Conceal">¦</span> <span class="Comment"># create invalid sandbox 2</span>
+<span id="L206" class="LineNr">206 </span>  <span class="Conceal">¦</span> type <span class="Constant">[get foo, x:offset]</span>
+<span id="L207" class="LineNr">207 </span>  <span class="Conceal">¦</span> press F4
+<span id="L208" class="LineNr">208 </span>  <span class="Conceal">¦</span> <span class="Comment"># create invalid sandbox 1</span>
+<span id="L209" class="LineNr">209 </span>  <span class="Conceal">¦</span> type <span class="Constant">[get foo, x:offset]</span>
+<span id="L210" class="LineNr">210 </span>  <span class="Conceal">¦</span> press F4
+<span id="L211" class="LineNr">211 </span>  <span class="Conceal">¦</span> <span class="Comment"># create valid sandbox 0</span>
+<span id="L212" class="LineNr">212 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>
+<span id="L213" class="LineNr">213 </span>  <span class="Conceal">¦</span> press F4
+<span id="L214" class="LineNr">214 </span>  ]
+<span id="L215" class="LineNr">215 </span>  run [
+<span id="L216" class="LineNr">216 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L217" class="LineNr">217 </span>  ]
+<span id="L218" class="LineNr">218 </span>  <span class="Comment"># status line shows that error is in second sandbox</span>
+<span id="L219" class="LineNr">219 </span>  screen-should-contain [
+<span id="L220" class="LineNr">220 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (1)                                                               run (F4)           .</span>
+<span id="L221" class="LineNr">221 </span>  ]
+<span id="L222" class="LineNr">222 </span>]
+<span id="L223" class="LineNr">223 </span>
+<span id="L224" class="LineNr">224 </span><span class="muScenario">scenario</span> run-hides-errors-from-past-sandboxes [
+<span id="L225" class="LineNr">225 </span>  <span class="Constant">local-scope</span>
+<span id="L226" class="LineNr">226 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L227" class="LineNr">227 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
+<span id="L228" class="LineNr">228 </span>  assume-resources [
+<span id="L229" class="LineNr">229 </span>  ]
+<span id="L230" class="LineNr">230 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[get foo, x:offset]</span>  <span class="Comment"># invalid</span>
+<span id="L231" class="LineNr">231 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L232" class="LineNr">232 </span>  assume-console [
+<span id="L233" class="LineNr">233 </span>  <span class="Conceal">¦</span> press F4  <span class="Comment"># generate error</span>
+<span id="L234" class="LineNr">234 </span>  ]
+<span id="L235" class="LineNr">235 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L236" class="LineNr">236 </span>  assume-console [
+<span id="L237" class="LineNr">237 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 3</span>,<span class="Constant"> 58</span>
+<span id="L238" class="LineNr">238 </span>  <span class="Conceal">¦</span> press ctrl-k
+<span id="L239" class="LineNr">239 </span>  <span class="Conceal">¦</span> type <span class="Constant">[add 2, 2]</span>  <span class="Comment"># valid code</span>
+<span id="L240" class="LineNr">240 </span>  <span class="Conceal">¦</span> press F4  <span class="Comment"># update sandbox</span>
+<span id="L241" class="LineNr">241 </span>  ]
+<span id="L242" class="LineNr">242 </span>  run [
+<span id="L243" class="LineNr">243 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L244" class="LineNr">244 </span>  ]
+<span id="L245" class="LineNr">245 </span>  <span class="Comment"># error should disappear</span>
+<span id="L246" class="LineNr">246 </span>  screen-should-contain [
+<span id="L247" class="LineNr">247 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                 run (F4)           .</span>
+<span id="L248" class="LineNr">248 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L249" class="LineNr">249 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L250" class="LineNr">250 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L251" class="LineNr">251 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎add 2, 2                                         .</span>
+<span id="L252" class="LineNr">252 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎4                                                .</span>
+<span id="L253" class="LineNr">253 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L254" class="LineNr">254 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L255" class="LineNr">255 </span>  ]
+<span id="L256" class="LineNr">256 </span>]
+<span id="L257" class="LineNr">257 </span>
+<span id="L258" class="LineNr">258 </span><span class="muScenario">scenario</span> run-updates-errors-for-shape-shifting-recipes [
+<span id="L259" class="LineNr">259 </span>  <span class="Constant">local-scope</span>
+<span id="L260" class="LineNr">260 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L261" class="LineNr">261 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
+<span id="L262" class="LineNr">262 </span>  <span class="Comment"># define a shape-shifting recipe with an error</span>
+<span id="L263" class="LineNr">263 </span>  assume-resources [
+<span id="L264" class="LineNr">264 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L265" class="LineNr">265 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo x:_elem<span class="muRecipe"> -&gt; </span>z:_elem <span class="Constant">[|</span>
+<span id="L266" class="LineNr">266 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  local-scope|</span>
+<span id="L267" class="LineNr">267 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  load-ingredients|</span>
+<span id="L268" class="LineNr">268 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  y:&amp;:num &lt;- copy 0|</span>
+<span id="L269" class="LineNr">269 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  z &lt;- add x, y|</span>
+<span id="L270" class="LineNr">270 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
+<span id="L271" class="LineNr">271 </span>  <span class="Conceal">¦</span> ]
+<span id="L272" class="LineNr">272 </span>  ]
+<span id="L273" class="LineNr">273 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo 2]</span>
+<span id="L274" class="LineNr">274 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L275" class="LineNr">275 </span>  assume-console [
+<span id="L276" class="LineNr">276 </span>  <span class="Conceal">¦</span> press F4
+<span id="L277" class="LineNr">277 </span>  ]
+<span id="L278" class="LineNr">278 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L279" class="LineNr">279 </span>  screen-should-contain [
+<span id="L280" class="LineNr">280 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
+<span id="L281" class="LineNr">281 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo x:_elem -&gt; z:_elem [                   ╎                                                 .</span>
+<span id="L282" class="LineNr">282 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L283" class="LineNr">283 </span>  <span class="Conceal">¦</span><span class="Constant"> .  load-ingredients                                ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L284" class="LineNr">284 </span>  <span class="Conceal">¦</span><span class="Constant"> .  y:&amp;:num &lt;- copy 0                               ╎foo 2                                            .</span>
+<span id="L285" class="LineNr">285 </span>  <span class="Conceal">¦</span><span class="Constant"> .  z &lt;- add x, y                                   ╎foo_2: 'add' requires number ingredients, but go↩.</span>
+<span id="L286" class="LineNr">286 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎t 'y'                                            .</span>
+<span id="L287" class="LineNr">287 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L288" class="LineNr">288 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L289" class="LineNr">289 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L290" class="LineNr">290 </span>  ]
+<span id="L291" class="LineNr">291 </span>  <span class="Comment"># now rerun everything</span>
+<span id="L292" class="LineNr">292 </span>  assume-console [
+<span id="L293" class="LineNr">293 </span>  <span class="Conceal">¦</span> press F4
 <span id="L294" class="LineNr">294 </span>  ]
-<span id="L295" class="LineNr">295 </span>  <span class="Comment"># error should remain unchanged</span>
-<span id="L296" class="LineNr">296 </span>  screen-should-contain [
-<span id="L297" class="LineNr">297 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
-<span id="L298" class="LineNr">298 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo x:_elem -&gt; z:_elem [                   ╎                                                 .</span>
-<span id="L299" class="LineNr">299 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L300" class="LineNr">300 </span>  <span class="Conceal">¦</span><span class="Constant"> .  load-ingredients                                ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L301" class="LineNr">301 </span>  <span class="Conceal">¦</span><span class="Constant"> .  y:&amp;:num &lt;- copy 0                               ╎foo 2                                            .</span>
-<span id="L302" class="LineNr">302 </span>  <span class="Conceal">¦</span><span class="Constant"> .  z &lt;- add x, y                                   ╎foo_3: 'add' requires number ingredients, but go↩.</span>
-<span id="L303" class="LineNr">303 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎t 'y'                                            .</span>
-<span id="L304" class="LineNr">304 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L305" class="LineNr">305 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L306" class="LineNr">306 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L307" class="LineNr">307 </span>  ]
-<span id="L308" class="LineNr">308 </span>]
-<span id="L309" class="LineNr">309 </span>
-<span id="L310" class="LineNr">310 </span><span class="muScenario">scenario</span> run-avoids-spurious-errors-on-reloading-shape-shifting-recipes [
-<span id="L311" class="LineNr">311 </span>  <span class="Constant">local-scope</span>
-<span id="L312" class="LineNr">312 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L313" class="LineNr">313 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
-<span id="L314" class="LineNr">314 </span>  <span class="Comment"># overload a well-known shape-shifting recipe</span>
-<span id="L315" class="LineNr">315 </span>  assume-resources [
-<span id="L316" class="LineNr">316 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
-<span id="L317" class="LineNr">317 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> length l:&amp;:<a href='../064list.mu.html#L6'>list</a>:_elem<span class="muRecipe"> -&gt; </span>n:num <span class="Constant">[|</span>
-<span id="L318" class="LineNr">318 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
-<span id="L319" class="LineNr">319 </span>  <span class="Conceal">¦</span> ]
-<span id="L320" class="LineNr">320 </span>  ]
-<span id="L321" class="LineNr">321 </span>  <span class="Comment"># call code that uses other variants of it, but not it itself</span>
-<span id="L322" class="LineNr">322 </span>  test-sandbox:text <span class="Special">&lt;-</span> new <span class="Constant">[x:&amp;:<a href='../064list.mu.html#L6'>list</a>:num &lt;- copy 0</span>
-<span id="L323" class="LineNr">323 </span><span class="Constant">to-text x]</span>
-<span id="L324" class="LineNr">324 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, test-sandbox
-<span id="L325" class="LineNr">325 </span>  <span class="Comment"># run it once</span>
-<span id="L326" class="LineNr">326 </span>  assume-console [
-<span id="L327" class="LineNr">327 </span>  <span class="Conceal">¦</span> press F4
-<span id="L328" class="LineNr">328 </span>  ]
-<span id="L329" class="LineNr">329 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L330" class="LineNr">330 </span>  <span class="Comment"># no errors anywhere on screen (can't check anything else, since to-text will return an address)</span>
-<span id="L331" class="LineNr">331 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
-<span id="L332" class="LineNr">332 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L333" class="LineNr">333 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L334" class="LineNr">334 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L335" class="LineNr">335 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L336" class="LineNr">336 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                &lt;-                                  .</span>
+<span id="L295" class="LineNr">295 </span>  run [
+<span id="L296" class="LineNr">296 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L297" class="LineNr">297 </span>  ]
+<span id="L298" class="LineNr">298 </span>  <span class="Comment"># error should remain unchanged</span>
+<span id="L299" class="LineNr">299 </span>  screen-should-contain [
+<span id="L300" class="LineNr">300 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
+<span id="L301" class="LineNr">301 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo x:_elem -&gt; z:_elem [                   ╎                                                 .</span>
+<span id="L302" class="LineNr">302 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L303" class="LineNr">303 </span>  <span class="Conceal">¦</span><span class="Constant"> .  load-ingredients                                ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L304" class="LineNr">304 </span>  <span class="Conceal">¦</span><span class="Constant"> .  y:&amp;:num &lt;- copy 0                               ╎foo 2                                            .</span>
+<span id="L305" class="LineNr">305 </span>  <span class="Conceal">¦</span><span class="Constant"> .  z &lt;- add x, y                                   ╎foo_3: 'add' requires number ingredients, but go↩.</span>
+<span id="L306" class="LineNr">306 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎t 'y'                                            .</span>
+<span id="L307" class="LineNr">307 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L308" class="LineNr">308 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L309" class="LineNr">309 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L310" class="LineNr">310 </span>  ]
+<span id="L311" class="LineNr">311 </span>]
+<span id="L312" class="LineNr">312 </span>
+<span id="L313" class="LineNr">313 </span><span class="muScenario">scenario</span> run-avoids-spurious-errors-on-reloading-shape-shifting-recipes [
+<span id="L314" class="LineNr">314 </span>  <span class="Constant">local-scope</span>
+<span id="L315" class="LineNr">315 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L316" class="LineNr">316 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
+<span id="L317" class="LineNr">317 </span>  <span class="Comment"># overload a well-known shape-shifting recipe</span>
+<span id="L318" class="LineNr">318 </span>  assume-resources [
+<span id="L319" class="LineNr">319 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L320" class="LineNr">320 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> length l:&amp;:<a href='../064list.mu.html#L6'>list</a>:_elem<span class="muRecipe"> -&gt; </span>n:num <span class="Constant">[|</span>
+<span id="L321" class="LineNr">321 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
+<span id="L322" class="LineNr">322 </span>  <span class="Conceal">¦</span> ]
+<span id="L323" class="LineNr">323 </span>  ]
+<span id="L324" class="LineNr">324 </span>  <span class="Comment"># call code that uses other variants of it, but not it itself</span>
+<span id="L325" class="LineNr">325 </span>  test-sandbox:text <span class="Special">&lt;-</span> new <span class="Constant">[x:&amp;:<a href='../064list.mu.html#L6'>list</a>:num &lt;- copy 0</span>
+<span id="L326" class="LineNr">326 </span><span class="Constant">to-text x]</span>
+<span id="L327" class="LineNr">327 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, test-sandbox
+<span id="L328" class="LineNr">328 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L329" class="LineNr">329 </span>  <span class="Comment"># run it once</span>
+<span id="L330" class="LineNr">330 </span>  assume-console [
+<span id="L331" class="LineNr">331 </span>  <span class="Conceal">¦</span> press F4
+<span id="L332" class="LineNr">332 </span>  ]
+<span id="L333" class="LineNr">333 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L334" class="LineNr">334 </span>  <span class="Comment"># no errors anywhere on screen (can't check anything else, since to-text will return an address)</span>
+<span id="L335" class="LineNr">335 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
+<span id="L336" class="LineNr">336 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L337" class="LineNr">337 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L338" class="LineNr">338 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L339" class="LineNr">339 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L340" class="LineNr">340 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L340" class="LineNr">340 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                &lt;-                                  .</span>
 <span id="L341" class="LineNr">341 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L342" class="LineNr">342 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L343" class="LineNr">343 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L344" class="LineNr">344 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L345" class="LineNr">345 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L346" class="LineNr">346 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L347" class="LineNr">347 </span>  ]
-<span id="L348" class="LineNr">348 </span>  <span class="Comment"># rerun everything</span>
-<span id="L349" class="LineNr">349 </span>  assume-console [
-<span id="L350" class="LineNr">350 </span>  <span class="Conceal">¦</span> press F4
+<span id="L347" class="LineNr">347 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L348" class="LineNr">348 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L349" class="LineNr">349 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L350" class="LineNr">350 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L351" class="LineNr">351 </span>  ]
-<span id="L352" class="LineNr">352 </span>  run [
-<span id="L353" class="LineNr">353 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L354" class="LineNr">354 </span>  ]
-<span id="L355" class="LineNr">355 </span>  <span class="Comment"># still no errors</span>
-<span id="L356" class="LineNr">356 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
-<span id="L357" class="LineNr">357 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L358" class="LineNr">358 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L359" class="LineNr">359 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L360" class="LineNr">360 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L361" class="LineNr">361 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                &lt;-                                  .</span>
+<span id="L352" class="LineNr">352 </span>  <span class="Comment"># rerun everything</span>
+<span id="L353" class="LineNr">353 </span>  assume-console [
+<span id="L354" class="LineNr">354 </span>  <span class="Conceal">¦</span> press F4
+<span id="L355" class="LineNr">355 </span>  ]
+<span id="L356" class="LineNr">356 </span>  run [
+<span id="L357" class="LineNr">357 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L358" class="LineNr">358 </span>  ]
+<span id="L359" class="LineNr">359 </span>  <span class="Comment"># still no errors</span>
+<span id="L360" class="LineNr">360 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
+<span id="L361" class="LineNr">361 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L362" class="LineNr">362 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L363" class="LineNr">363 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L364" class="LineNr">364 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L365" class="LineNr">365 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L365" class="LineNr">365 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                &lt;-                                  .</span>
 <span id="L366" class="LineNr">366 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L367" class="LineNr">367 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L368" class="LineNr">368 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L369" class="LineNr">369 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L370" class="LineNr">370 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L371" class="LineNr">371 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L372" class="LineNr">372 </span>  ]
-<span id="L373" class="LineNr">373 </span>]
-<span id="L374" class="LineNr">374 </span>
-<span id="L375" class="LineNr">375 </span><span class="muScenario">scenario</span> run-shows-missing-type-errors [
-<span id="L376" class="LineNr">376 </span>  <span class="Constant">local-scope</span>
-<span id="L377" class="LineNr">377 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L378" class="LineNr">378 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
-<span id="L379" class="LineNr">379 </span>  assume-resources [
-<span id="L380" class="LineNr">380 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
-<span id="L381" class="LineNr">381 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
-<span id="L382" class="LineNr">382 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  x &lt;- copy 0|</span>
-<span id="L383" class="LineNr">383 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
-<span id="L384" class="LineNr">384 </span>  <span class="Conceal">¦</span> ]
-<span id="L385" class="LineNr">385 </span>  ]
-<span id="L386" class="LineNr">386 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
-<span id="L387" class="LineNr">387 </span>  assume-console [
-<span id="L388" class="LineNr">388 </span>  <span class="Conceal">¦</span> press F4
+<span id="L372" class="LineNr">372 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L373" class="LineNr">373 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L374" class="LineNr">374 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L375" class="LineNr">375 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L376" class="LineNr">376 </span>  ]
+<span id="L377" class="LineNr">377 </span>]
+<span id="L378" class="LineNr">378 </span>
+<span id="L379" class="LineNr">379 </span><span class="muScenario">scenario</span> run-shows-missing-type-errors [
+<span id="L380" class="LineNr">380 </span>  <span class="Constant">local-scope</span>
+<span id="L381" class="LineNr">381 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L382" class="LineNr">382 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
+<span id="L383" class="LineNr">383 </span>  assume-resources [
+<span id="L384" class="LineNr">384 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L385" class="LineNr">385 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
+<span id="L386" class="LineNr">386 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  x &lt;- copy 0|</span>
+<span id="L387" class="LineNr">387 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
+<span id="L388" class="LineNr">388 </span>  <span class="Conceal">¦</span> ]
 <span id="L389" class="LineNr">389 </span>  ]
-<span id="L390" class="LineNr">390 </span>  run [
-<span id="L391" class="LineNr">391 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L392" class="LineNr">392 </span>  ]
-<span id="L393" class="LineNr">393 </span>  screen-should-contain [
-<span id="L394" class="LineNr">394 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
-<span id="L395" class="LineNr">395 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
-<span id="L396" class="LineNr">396 </span>  <span class="Conceal">¦</span><span class="Constant"> .  x &lt;- copy 0                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L397" class="LineNr">397 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
-<span id="L398" class="LineNr">398 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L399" class="LineNr">399 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: missing type for 'x' in 'x &lt;- copy 0'        ╎                                                 .</span>
-<span id="L400" class="LineNr">400 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: can't copy '0' to 'x'; types don't <a href='../065duplex_list.mu.html#L589'>match</a>     ╎                                                 .</span>
-<span id="L401" class="LineNr">401 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L402" class="LineNr">402 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
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-<span id="L426" class="LineNr">426 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo \\[                                      ╎foo                                              .</span>
-<span id="L427" class="LineNr">427 </span>  <span class="Conceal">¦</span><span class="Constant"> .  x &lt;- copy 0                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L428" class="LineNr">428 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L429" class="LineNr">429 </span>  <span class="Conceal">¦</span><span class="Constant"> .9: unbalanced '\\[' for recipe                      ╎                                                 .</span>
-<span id="L430" class="LineNr">430 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L431" class="LineNr">431 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
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-<span id="L457" class="LineNr">457 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
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-<span id="L462" class="LineNr">462 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L463" class="LineNr">463 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: first ingredient of 'get' should be a contai↩╎                                                 .</span>
-<span id="L464" class="LineNr">464 </span>  <span class="Conceal">¦</span><span class="Constant"> .ner, but got 'x:&amp;:point'                          ╎                                                 .</span>
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-<span id="L466" class="LineNr">466 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
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+<span id="L397" class="LineNr">397 </span>  ]
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+<span id="L400" class="LineNr">400 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
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+<span id="L403" class="LineNr">403 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L404" class="LineNr">404 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: missing type for 'x' in 'x &lt;- copy 0'        ╎                                                 .</span>
+<span id="L405" class="LineNr">405 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: can't copy '0' to 'x'; types don't <a href='../065duplex_list.mu.html#L589'>match</a>     ╎                                                 .</span>
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+<span id="L407" class="LineNr">407 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
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+<span id="L415" class="LineNr">415 </span>  <span class="Comment"># recipe is incomplete (unbalanced '[')</span>
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+<span id="L424" class="LineNr">424 </span>  assume-console [
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+<span id="L429" class="LineNr">429 </span>  ]
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+<span id="L437" class="LineNr">437 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
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+<span id="L451" class="LineNr">451 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
+<span id="L452" class="LineNr">452 </span>  <span class="Conceal">¦</span> ]
+<span id="L453" class="LineNr">453 </span>  ]
+<span id="L454" class="LineNr">454 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
+<span id="L455" class="LineNr">455 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L456" class="LineNr">456 </span>  assume-console [
+<span id="L457" class="LineNr">457 </span>  <span class="Conceal">¦</span> press F4
+<span id="L458" class="LineNr">458 </span>  ]
+<span id="L459" class="LineNr">459 </span>  run [
+<span id="L460" class="LineNr">460 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L461" class="LineNr">461 </span>  ]
+<span id="L462" class="LineNr">462 </span>  screen-should-contain [
+<span id="L463" class="LineNr">463 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
+<span id="L464" class="LineNr">464 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
+<span id="L465" class="LineNr">465 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L466" class="LineNr">466 </span>  <span class="Conceal">¦</span><span class="Constant"> .  x:&amp;:point &lt;- new point:type                     ╎                                                 .</span>
+<span id="L467" class="LineNr">467 </span>  <span class="Conceal">¦</span><span class="Constant"> .  get x:&amp;:point, 1:offset                         ╎                                                 .</span>
+<span id="L468" class="LineNr">468 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
+<span id="L469" class="LineNr">469 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L470" class="LineNr">470 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: first ingredient of 'get' should be a contai↩╎                                                 .</span>
+<span id="L471" class="LineNr">471 </span>  <span class="Conceal">¦</span><span class="Constant"> .ner, but got 'x:&amp;:point'                          ╎                                                 .</span>
+<span id="L472" class="LineNr">472 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L473" class="LineNr">473 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L474" class="LineNr">474 </span>  ]
+<span id="L475" class="LineNr">475 </span>]
+<span id="L476" class="LineNr">476 </span>
+<span id="L477" class="LineNr">477 </span><span class="muScenario">scenario</span> run-shows-non-literal-get-argument-errors [
+<span id="L478" class="LineNr">478 </span>  <span class="Constant">local-scope</span>
+<span id="L479" class="LineNr">479 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L480" class="LineNr">480 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
+<span id="L481" class="LineNr">481 </span>  assume-resources [
+<span id="L482" class="LineNr">482 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L483" class="LineNr">483 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
+<span id="L484" class="LineNr">484 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  local-scope|</span>
+<span id="L485" class="LineNr">485 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  x:num &lt;- copy 0|</span>
+<span id="L486" class="LineNr">486 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  y:&amp;:point &lt;- new point:type|</span>
+<span id="L487" class="LineNr">487 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  get *y:&amp;:point, x:num|</span>
+<span id="L488" class="LineNr">488 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
+<span id="L489" class="LineNr">489 </span>  <span class="Conceal">¦</span> ]
 <span id="L490" class="LineNr">490 </span>  ]
-<span id="L491" class="LineNr">491 </span>  screen-should-contain [
-<span id="L492" class="LineNr">492 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
-<span id="L493" class="LineNr">493 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
-<span id="L494" class="LineNr">494 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L495" class="LineNr">495 </span>  <span class="Conceal">¦</span><span class="Constant"> .  x:num &lt;- copy 0                                 ╎                                                 .</span>
-<span id="L496" class="LineNr">496 </span>  <span class="Conceal">¦</span><span class="Constant"> .  y:&amp;:point &lt;- new point:type                     ╎                                                 .</span>
-<span id="L497" class="LineNr">497 </span>  <span class="Conceal">¦</span><span class="Constant"> .  get *y:&amp;:point, x:num                           ╎                                                 .</span>
-<span id="L498" class="LineNr">498 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
-<span id="L499" class="LineNr">499 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L500" class="LineNr">500 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: second ingredient of 'get' should have type ↩╎                                                 .</span>
-<span id="L501" class="LineNr">501 </span>  <span class="Conceal">¦</span><span class="Constant"> .'offset', but got 'x:num'                         ╎                                                 .</span>
-<span id="L502" class="LineNr">502 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L503" class="LineNr">503 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L504" class="LineNr">504 </span>  ]
-<span id="L505" class="LineNr">505 </span>]
-<span id="L506" class="LineNr">506 </span>
-<span id="L507" class="LineNr">507 </span><span class="muScenario">scenario</span> run-shows-errors-everytime [
-<span id="L508" class="LineNr">508 </span>  <span class="Constant">local-scope</span>
-<span id="L509" class="LineNr">509 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L510" class="LineNr">510 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
-<span id="L511" class="LineNr">511 </span>  <span class="Comment"># try to run a file with an error</span>
-<span id="L512" class="LineNr">512 </span>  assume-resources [
-<span id="L513" class="LineNr">513 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
-<span id="L514" class="LineNr">514 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
-<span id="L515" class="LineNr">515 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  local-scope|</span>
-<span id="L516" class="LineNr">516 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  x:num &lt;- copy y:num|</span>
-<span id="L517" class="LineNr">517 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
-<span id="L518" class="LineNr">518 </span>  <span class="Conceal">¦</span> ]
-<span id="L519" class="LineNr">519 </span>  ]
-<span id="L520" class="LineNr">520 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
-<span id="L521" class="LineNr">521 </span>  assume-console [
-<span id="L522" class="LineNr">522 </span>  <span class="Conceal">¦</span> press F4
-<span id="L523" class="LineNr">523 </span>  ]
-<span id="L524" class="LineNr">524 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L525" class="LineNr">525 </span>  screen-should-contain [
-<span id="L526" class="LineNr">526 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
-<span id="L527" class="LineNr">527 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
-<span id="L528" class="LineNr">528 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L529" class="LineNr">529 </span>  <span class="Conceal">¦</span><span class="Constant"> .  x:num &lt;- copy y:num                             ╎                                                 .</span>
-<span id="L530" class="LineNr">530 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
-<span id="L531" class="LineNr">531 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L532" class="LineNr">532 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: tried to read ingredient 'y' in 'x:num &lt;- co↩╎                                                 .</span>
-<span id="L533" class="LineNr">533 </span>  <span class="Conceal">¦</span><span class="Constant"> .py y:num' but it hasn't been written to yet       ╎                                                 .</span>
-<span id="L534" class="LineNr">534 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L535" class="LineNr">535 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L536" class="LineNr">536 </span>  ]
-<span id="L537" class="LineNr">537 </span>  <span class="Comment"># rerun the file, check for the same error</span>
-<span id="L538" class="LineNr">538 </span>  assume-console [
-<span id="L539" class="LineNr">539 </span>  <span class="Conceal">¦</span> press F4
-<span id="L540" class="LineNr">540 </span>  ]
-<span id="L541" class="LineNr">541 </span>  run [
-<span id="L542" class="LineNr">542 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L543" class="LineNr">543 </span>  ]
-<span id="L544" class="LineNr">544 </span>  screen-should-contain [
-<span id="L545" class="LineNr">545 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
-<span id="L546" class="LineNr">546 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
-<span id="L547" class="LineNr">547 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L548" class="LineNr">548 </span>  <span class="Conceal">¦</span><span class="Constant"> .  x:num &lt;- copy y:num                             ╎                                                 .</span>
-<span id="L549" class="LineNr">549 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
-<span id="L550" class="LineNr">550 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L551" class="LineNr">551 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: tried to read ingredient 'y' in 'x:num &lt;- co↩╎                                                 .</span>
-<span id="L552" class="LineNr">552 </span>  <span class="Conceal">¦</span><span class="Constant"> .py y:num' but it hasn't been written to yet       ╎                                                 .</span>
-<span id="L553" class="LineNr">553 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L554" class="LineNr">554 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L555" class="LineNr">555 </span>  ]
-<span id="L556" class="LineNr">556 </span>]
-<span id="L557" class="LineNr">557 </span>
-<span id="L558" class="LineNr">558 </span><span class="muScenario">scenario</span> run-instruction-and-print-errors [
-<span id="L559" class="LineNr">559 </span>  <span class="Constant">local-scope</span>
-<span id="L560" class="LineNr">560 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L561" class="LineNr">561 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L562" class="LineNr">562 </span>  assume-resources [
-<span id="L563" class="LineNr">563 </span>  ]
-<span id="L564" class="LineNr">564 </span>  <span class="Comment"># sandbox editor contains an illegal instruction</span>
-<span id="L565" class="LineNr">565 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[get 1234:num, foo:offset]</span>
-<span id="L566" class="LineNr">566 </span>  assume-console [
-<span id="L567" class="LineNr">567 </span>  <span class="Conceal">¦</span> press F4
-<span id="L568" class="LineNr">568 </span>  ]
-<span id="L569" class="LineNr">569 </span>  run [
-<span id="L570" class="LineNr">570 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L571" class="LineNr">571 </span>  ]
-<span id="L572" class="LineNr">572 </span>  <span class="Comment"># check that screen prints error message in red</span>
-<span id="L573" class="LineNr">573 </span>  screen-should-contain [
-<span id="L574" class="LineNr">574 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
-<span id="L575" class="LineNr">575 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L576" class="LineNr">576 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L577" class="LineNr">577 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L578" class="LineNr">578 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎get 1234:num, foo:offset                         .</span>
-<span id="L579" class="LineNr">579 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎unknown element 'foo' in container 'number'      .</span>
-<span id="L580" class="LineNr">580 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎first ingredient of 'get' should be a container,↩.</span>
-<span id="L581" class="LineNr">581 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎ but got '1234:num'                              .</span>
-<span id="L582" class="LineNr">582 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L583" class="LineNr">583 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L584" class="LineNr">584 </span>  ]
-<span id="L585" class="LineNr">585 </span>  screen-should-contain-in-color <span class="Constant">7/white</span>, [
-<span id="L586" class="LineNr">586 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L587" class="LineNr">587 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L588" class="LineNr">588 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L589" class="LineNr">589 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L590" class="LineNr">590 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   get 1234:num, foo:offset                         .</span>
-<span id="L591" class="LineNr">591 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L592" class="LineNr">592 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L593" class="LineNr">593 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L491" class="LineNr">491 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
+<span id="L492" class="LineNr">492 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L493" class="LineNr">493 </span>  assume-console [
+<span id="L494" class="LineNr">494 </span>  <span class="Conceal">¦</span> press F4
+<span id="L495" class="LineNr">495 </span>  ]
+<span id="L496" class="LineNr">496 </span>  run [
+<span id="L497" class="LineNr">497 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L498" class="LineNr">498 </span>  ]
+<span id="L499" class="LineNr">499 </span>  screen-should-contain [
+<span id="L500" class="LineNr">500 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
+<span id="L501" class="LineNr">501 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
+<span id="L502" class="LineNr">502 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L503" class="LineNr">503 </span>  <span class="Conceal">¦</span><span class="Constant"> .  x:num &lt;- copy 0                                 ╎                                                 .</span>
+<span id="L504" class="LineNr">504 </span>  <span class="Conceal">¦</span><span class="Constant"> .  y:&amp;:point &lt;- new point:type                     ╎                                                 .</span>
+<span id="L505" class="LineNr">505 </span>  <span class="Conceal">¦</span><span class="Constant"> .  get *y:&amp;:point, x:num                           ╎                                                 .</span>
+<span id="L506" class="LineNr">506 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
+<span id="L507" class="LineNr">507 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L508" class="LineNr">508 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: second ingredient of 'get' should have type ↩╎                                                 .</span>
+<span id="L509" class="LineNr">509 </span>  <span class="Conceal">¦</span><span class="Constant"> .'offset', but got 'x:num'                         ╎                                                 .</span>
+<span id="L510" class="LineNr">510 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L511" class="LineNr">511 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L512" class="LineNr">512 </span>  ]
+<span id="L513" class="LineNr">513 </span>]
+<span id="L514" class="LineNr">514 </span>
+<span id="L515" class="LineNr">515 </span><span class="muScenario">scenario</span> run-shows-errors-everytime [
+<span id="L516" class="LineNr">516 </span>  <span class="Constant">local-scope</span>
+<span id="L517" class="LineNr">517 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L518" class="LineNr">518 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">15/height</span>
+<span id="L519" class="LineNr">519 </span>  <span class="Comment"># try to run a file with an error</span>
+<span id="L520" class="LineNr">520 </span>  assume-resources [
+<span id="L521" class="LineNr">521 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L522" class="LineNr">522 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
+<span id="L523" class="LineNr">523 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  local-scope|</span>
+<span id="L524" class="LineNr">524 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  x:num &lt;- copy y:num|</span>
+<span id="L525" class="LineNr">525 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
+<span id="L526" class="LineNr">526 </span>  <span class="Conceal">¦</span> ]
+<span id="L527" class="LineNr">527 </span>  ]
+<span id="L528" class="LineNr">528 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
+<span id="L529" class="LineNr">529 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L530" class="LineNr">530 </span>  assume-console [
+<span id="L531" class="LineNr">531 </span>  <span class="Conceal">¦</span> press F4
+<span id="L532" class="LineNr">532 </span>  ]
+<span id="L533" class="LineNr">533 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L534" class="LineNr">534 </span>  screen-should-contain [
+<span id="L535" class="LineNr">535 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
+<span id="L536" class="LineNr">536 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
+<span id="L537" class="LineNr">537 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L538" class="LineNr">538 </span>  <span class="Conceal">¦</span><span class="Constant"> .  x:num &lt;- copy y:num                             ╎                                                 .</span>
+<span id="L539" class="LineNr">539 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
+<span id="L540" class="LineNr">540 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L541" class="LineNr">541 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: tried to read ingredient 'y' in 'x:num &lt;- co↩╎                                                 .</span>
+<span id="L542" class="LineNr">542 </span>  <span class="Conceal">¦</span><span class="Constant"> .py y:num' but it hasn't been written to yet       ╎                                                 .</span>
+<span id="L543" class="LineNr">543 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L544" class="LineNr">544 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L545" class="LineNr">545 </span>  ]
+<span id="L546" class="LineNr">546 </span>  <span class="Comment"># rerun the file, check for the same error</span>
+<span id="L547" class="LineNr">547 </span>  assume-console [
+<span id="L548" class="LineNr">548 </span>  <span class="Conceal">¦</span> press F4
+<span id="L549" class="LineNr">549 </span>  ]
+<span id="L550" class="LineNr">550 </span>  run [
+<span id="L551" class="LineNr">551 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L552" class="LineNr">552 </span>  ]
+<span id="L553" class="LineNr">553 </span>  screen-should-contain [
+<span id="L554" class="LineNr">554 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found                                                                   run (F4)           .</span>
+<span id="L555" class="LineNr">555 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎foo                                              .</span>
+<span id="L556" class="LineNr">556 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L557" class="LineNr">557 </span>  <span class="Conceal">¦</span><span class="Constant"> .  x:num &lt;- copy y:num                             ╎                                                 .</span>
+<span id="L558" class="LineNr">558 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
+<span id="L559" class="LineNr">559 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L560" class="LineNr">560 </span>  <span class="Conceal">¦</span><span class="Constant"> .foo: tried to read ingredient 'y' in 'x:num &lt;- co↩╎                                                 .</span>
+<span id="L561" class="LineNr">561 </span>  <span class="Conceal">¦</span><span class="Constant"> .py y:num' but it hasn't been written to yet       ╎                                                 .</span>
+<span id="L562" class="LineNr">562 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L563" class="LineNr">563 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L564" class="LineNr">564 </span>  ]
+<span id="L565" class="LineNr">565 </span>]
+<span id="L566" class="LineNr">566 </span>
+<span id="L567" class="LineNr">567 </span><span class="muScenario">scenario</span> run-instruction-and-print-errors [
+<span id="L568" class="LineNr">568 </span>  <span class="Constant">local-scope</span>
+<span id="L569" class="LineNr">569 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L570" class="LineNr">570 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L571" class="LineNr">571 </span>  assume-resources [
+<span id="L572" class="LineNr">572 </span>  ]
+<span id="L573" class="LineNr">573 </span>  <span class="Comment"># sandbox editor contains an illegal instruction</span>
+<span id="L574" class="LineNr">574 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[get 1234:num, foo:offset]</span>
+<span id="L575" class="LineNr">575 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L576" class="LineNr">576 </span>  assume-console [
+<span id="L577" class="LineNr">577 </span>  <span class="Conceal">¦</span> press F4
+<span id="L578" class="LineNr">578 </span>  ]
+<span id="L579" class="LineNr">579 </span>  run [
+<span id="L580" class="LineNr">580 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L581" class="LineNr">581 </span>  ]
+<span id="L582" class="LineNr">582 </span>  <span class="Comment"># check that screen prints error message in red</span>
+<span id="L583" class="LineNr">583 </span>  screen-should-contain [
+<span id="L584" class="LineNr">584 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
+<span id="L585" class="LineNr">585 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L586" class="LineNr">586 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L587" class="LineNr">587 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L588" class="LineNr">588 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎get 1234:num, foo:offset                         .</span>
+<span id="L589" class="LineNr">589 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎unknown element 'foo' in container 'number'      .</span>
+<span id="L590" class="LineNr">590 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎first ingredient of 'get' should be a container,↩.</span>
+<span id="L591" class="LineNr">591 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎ but got '1234:num'                              .</span>
+<span id="L592" class="LineNr">592 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L593" class="LineNr">593 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
 <span id="L594" class="LineNr">594 </span>  ]
-<span id="L595" class="LineNr">595 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
-<span id="L596" class="LineNr">596 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                                                  .</span>
+<span id="L595" class="LineNr">595 </span>  screen-should-contain-in-color <span class="Constant">7/white</span>, [
+<span id="L596" class="LineNr">596 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L597" class="LineNr">597 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L598" class="LineNr">598 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
 <span id="L599" class="LineNr">599 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L600" class="LineNr">600 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L601" class="LineNr">601 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   unknown element 'foo' in container 'number'      .</span>
-<span id="L602" class="LineNr">602 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   first ingredient of 'get' should be a container, .</span>
-<span id="L603" class="LineNr">603 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                    but got '1234:num'                              .</span>
-<span id="L604" class="LineNr">604 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L605" class="LineNr">605 </span>  ]
-<span id="L606" class="LineNr">606 </span>  screen-should-contain-in-color <span class="Constant">245/grey</span>, [
+<span id="L600" class="LineNr">600 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   get 1234:num, foo:offset                         .</span>
+<span id="L601" class="LineNr">601 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L602" class="LineNr">602 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L603" class="LineNr">603 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L604" class="LineNr">604 </span>  ]
+<span id="L605" class="LineNr">605 </span>  screen-should-contain-in-color <span class="Constant">1/red</span>, [
+<span id="L606" class="LineNr">606 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                                                  .</span>
 <span id="L607" class="LineNr">607 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
-<span id="L608" class="LineNr">608 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L609" class="LineNr">609 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L610" class="LineNr">610 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L611" class="LineNr">611 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L612" class="LineNr">612 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L613" class="LineNr">613 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                ↩.</span>
-<span id="L614" class="LineNr">614 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L615" class="LineNr">615 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L616" class="LineNr">616 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L617" class="LineNr">617 </span>  ]
-<span id="L618" class="LineNr">618 </span>]
-<span id="L619" class="LineNr">619 </span>
-<span id="L620" class="LineNr">620 </span><span class="muScenario">scenario</span> run-instruction-and-print-errors-only-once [
-<span id="L621" class="LineNr">621 </span>  <span class="Constant">local-scope</span>
-<span id="L622" class="LineNr">622 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L623" class="LineNr">623 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L624" class="LineNr">624 </span>  assume-resources [
-<span id="L625" class="LineNr">625 </span>  ]
-<span id="L626" class="LineNr">626 </span>  <span class="Comment"># sandbox editor contains an illegal instruction</span>
-<span id="L627" class="LineNr">627 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[get 1234:num, foo:offset]</span>
-<span id="L628" class="LineNr">628 </span>  <span class="Comment"># run the code in the editors multiple times</span>
-<span id="L629" class="LineNr">629 </span>  assume-console [
-<span id="L630" class="LineNr">630 </span>  <span class="Conceal">¦</span> press F4
-<span id="L631" class="LineNr">631 </span>  <span class="Conceal">¦</span> press F4
-<span id="L632" class="LineNr">632 </span>  ]
-<span id="L633" class="LineNr">633 </span>  run [
-<span id="L634" class="LineNr">634 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L608" class="LineNr">608 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L609" class="LineNr">609 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L610" class="LineNr">610 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L611" class="LineNr">611 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   unknown element 'foo' in container 'number'      .</span>
+<span id="L612" class="LineNr">612 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                   first ingredient of 'get' should be a container, .</span>
+<span id="L613" class="LineNr">613 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                    but got '1234:num'                              .</span>
+<span id="L614" class="LineNr">614 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L615" class="LineNr">615 </span>  ]
+<span id="L616" class="LineNr">616 </span>  screen-should-contain-in-color <span class="Constant">245/grey</span>, [
+<span id="L617" class="LineNr">617 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                                                                    .</span>
+<span id="L618" class="LineNr">618 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L619" class="LineNr">619 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L620" class="LineNr">620 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L621" class="LineNr">621 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L622" class="LineNr">622 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L623" class="LineNr">623 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                ↩.</span>
+<span id="L624" class="LineNr">624 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L625" class="LineNr">625 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L626" class="LineNr">626 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L627" class="LineNr">627 </span>  ]
+<span id="L628" class="LineNr">628 </span>]
+<span id="L629" class="LineNr">629 </span>
+<span id="L630" class="LineNr">630 </span><span class="muScenario">scenario</span> run-instruction-and-print-errors-only-once [
+<span id="L631" class="LineNr">631 </span>  <span class="Constant">local-scope</span>
+<span id="L632" class="LineNr">632 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L633" class="LineNr">633 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L634" class="LineNr">634 </span>  assume-resources [
 <span id="L635" class="LineNr">635 </span>  ]
-<span id="L636" class="LineNr">636 </span>  <span class="Comment"># check that screen prints error message just once</span>
-<span id="L637" class="LineNr">637 </span>  screen-should-contain [
-<span id="L638" class="LineNr">638 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
-<span id="L639" class="LineNr">639 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L640" class="LineNr">640 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
-<span id="L641" class="LineNr">641 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L642" class="LineNr">642 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎get 1234:num, foo:offset                         .</span>
-<span id="L643" class="LineNr">643 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎unknown element 'foo' in container 'number'      .</span>
-<span id="L644" class="LineNr">644 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎first ingredient of 'get' should be a container,↩.</span>
-<span id="L645" class="LineNr">645 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎ but got '1234:num'                              .</span>
-<span id="L646" class="LineNr">646 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L647" class="LineNr">647 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L648" class="LineNr">648 </span>  ]
-<span id="L649" class="LineNr">649 </span>]
-<span id="L650" class="LineNr">650 </span>
-<span id="L651" class="LineNr">651 </span><span class="muScenario">scenario</span> sandbox-can-handle-infinite-loop [
-<span id="L652" class="LineNr">652 </span>  <span class="Constant">local-scope</span>
-<span id="L653" class="LineNr">653 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L654" class="LineNr">654 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">20/height</span>
-<span id="L655" class="LineNr">655 </span>  <span class="Comment"># sandbox editor will trigger an infinite loop</span>
-<span id="L656" class="LineNr">656 </span>  assume-resources [
-<span id="L657" class="LineNr">657 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
-<span id="L658" class="LineNr">658 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
-<span id="L659" class="LineNr">659 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  {|</span>
-<span id="L660" class="LineNr">660 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |    loop|</span>
-<span id="L661" class="LineNr">661 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  }|</span>
-<span id="L662" class="LineNr">662 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
-<span id="L663" class="LineNr">663 </span>  <span class="Conceal">¦</span> ]
-<span id="L664" class="LineNr">664 </span>  ]
-<span id="L665" class="LineNr">665 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
-<span id="L666" class="LineNr">666 </span>  <span class="Comment"># run the sandbox</span>
-<span id="L667" class="LineNr">667 </span>  assume-console [
-<span id="L668" class="LineNr">668 </span>  <span class="Conceal">¦</span> press F4
-<span id="L669" class="LineNr">669 </span>  ]
-<span id="L670" class="LineNr">670 </span>  run [
-<span id="L671" class="LineNr">671 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L672" class="LineNr">672 </span>  ]
-<span id="L673" class="LineNr">673 </span>  screen-should-contain [
-<span id="L674" class="LineNr">674 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
-<span id="L675" class="LineNr">675 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
-<span id="L676" class="LineNr">676 </span>  <span class="Conceal">¦</span><span class="Constant"> .  {                                               ╎─────────────────────────────────────────────────.</span>
-<span id="L677" class="LineNr">677 </span>  <span class="Conceal">¦</span><span class="Constant"> .    loop                                          ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L678" class="LineNr">678 </span>  <span class="Conceal">¦</span><span class="Constant"> .  }                                               ╎foo                                              .</span>
-<span id="L679" class="LineNr">679 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎took too long!                                   .</span>
-<span id="L680" class="LineNr">680 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
-<span id="L681" class="LineNr">681 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
-<span id="L682" class="LineNr">682 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L683" class="LineNr">683 </span>  ]
-<span id="L684" class="LineNr">684 </span>]
-<span id="L685" class="LineNr">685 </span>
-<span id="L686" class="LineNr">686 </span><span class="muScenario">scenario</span> sandbox-with-errors-shows-trace [
-<span id="L687" class="LineNr">687 </span>  <span class="Constant">local-scope</span>
-<span id="L688" class="LineNr">688 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-<span id="L689" class="LineNr">689 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
-<span id="L690" class="LineNr">690 </span>  <span class="Comment"># generate a stash and a error</span>
-<span id="L691" class="LineNr">691 </span>  assume-resources [
-<span id="L692" class="LineNr">692 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
-<span id="L693" class="LineNr">693 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
-<span id="L694" class="LineNr">694 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  local-scope|</span>
-<span id="L695" class="LineNr">695 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  a:num &lt;- next-ingredient|</span>
-<span id="L696" class="LineNr">696 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  b:num &lt;- next-ingredient|</span>
-<span id="L697" class="LineNr">697 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  stash [dividing by]</span>, b|
-<span id="L698" class="LineNr">698 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|</span>  _, c:num <span class="Special">&lt;-</span> divide-with-remainder a, b|
-<span id="L699" class="LineNr">699 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|</span>  <span class="muControl">reply</span> b|
-<span id="L700" class="LineNr">700 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]|</span>
-<span id="L701" class="LineNr">701 </span>  <span class="Conceal">¦</span> ]
-<span id="L702" class="LineNr">702 </span>  ]
-<span id="L703" class="LineNr">703 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo 4, 0]</span>
-<span id="L704" class="LineNr">704 </span>  <span class="Comment"># run</span>
-<span id="L705" class="LineNr">705 </span>  assume-console [
-<span id="L706" class="LineNr">706 </span>  <span class="Conceal">¦</span> press F4
-<span id="L707" class="LineNr">707 </span>  ]
-<span id="L708" class="LineNr">708 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L709" class="LineNr">709 </span>  <span class="Comment"># screen prints error message</span>
-<span id="L710" class="LineNr">710 </span>  screen-should-contain [
-<span id="L711" class="LineNr">711 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
-<span id="L712" class="LineNr">712 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
-<span id="L713" class="LineNr">713 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L714" class="LineNr">714 </span>  <span class="Conceal">¦</span><span class="Constant"> .  a:num &lt;- next-ingredient                        ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L715" class="LineNr">715 </span>  <span class="Conceal">¦</span><span class="Constant"> .  b:num &lt;- next-ingredient                        ╎foo 4, 0                                         .</span>
-<span id="L716" class="LineNr">716 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [dividing by], b                          ╎foo: divide by zero in '_, c:num &lt;- divide-with-↩.</span>
-<span id="L717" class="LineNr">717 </span>  <span class="Conceal">¦</span><span class="Constant"> .  _, c:num &lt;- divide-with-remainder a, b          ╎remainder a, b'                                  .</span>
-<span id="L718" class="LineNr">718 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply b                                         ╎─────────────────────────────────────────────────.</span>
-<span id="L719" class="LineNr">719 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
-<span id="L720" class="LineNr">720 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
-<span id="L721" class="LineNr">721 </span>  ]
-<span id="L722" class="LineNr">722 </span>  <span class="Comment"># click on the call in the sandbox</span>
-<span id="L723" class="LineNr">723 </span>  assume-console [
-<span id="L724" class="LineNr">724 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 55</span>
-<span id="L725" class="LineNr">725 </span>  ]
-<span id="L726" class="LineNr">726 </span>  run [
-<span id="L727" class="LineNr">727 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
-<span id="L728" class="LineNr">728 </span>  ]
-<span id="L729" class="LineNr">729 </span>  <span class="Comment"># screen should expand trace</span>
-<span id="L730" class="LineNr">730 </span>  screen-should-contain [
-<span id="L731" class="LineNr">731 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
-<span id="L732" class="LineNr">732 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
-<span id="L733" class="LineNr">733 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
-<span id="L734" class="LineNr">734 </span>  <span class="Conceal">¦</span><span class="Constant"> .  a:num &lt;- next-ingredient                        ╎0   edit       copy       to recipe    delete    .</span>
-<span id="L735" class="LineNr">735 </span>  <span class="Conceal">¦</span><span class="Constant"> .  b:num &lt;- next-ingredient                        ╎foo 4, 0                                         .</span>
-<span id="L736" class="LineNr">736 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [dividing by], b                          ╎dividing by 0                                    .</span>
-<span id="L737" class="LineNr">737 </span>  <span class="Conceal">¦</span><span class="Constant"> .  _, c:num &lt;- divide-with-remainder a, b          ╎14 instructions run                              .</span>
-<span id="L738" class="LineNr">738 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply b                                         ╎foo: divide by zero in '_, c:num &lt;- divide-with-↩.</span>
-<span id="L739" class="LineNr">739 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎remainder a, b'                                  .</span>
-<span id="L740" class="LineNr">740 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L636" class="LineNr">636 </span>  <span class="Comment"># sandbox editor contains an illegal instruction</span>
+<span id="L637" class="LineNr">637 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[get 1234:num, foo:offset]</span>
+<span id="L638" class="LineNr">638 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L639" class="LineNr">639 </span>  <span class="Comment"># run the code in the editors multiple times</span>
+<span id="L640" class="LineNr">640 </span>  assume-console [
+<span id="L641" class="LineNr">641 </span>  <span class="Conceal">¦</span> press F4
+<span id="L642" class="LineNr">642 </span>  <span class="Conceal">¦</span> press F4
+<span id="L643" class="LineNr">643 </span>  ]
+<span id="L644" class="LineNr">644 </span>  run [
+<span id="L645" class="LineNr">645 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L646" class="LineNr">646 </span>  ]
+<span id="L647" class="LineNr">647 </span>  <span class="Comment"># check that screen prints error message just once</span>
+<span id="L648" class="LineNr">648 </span>  screen-should-contain [
+<span id="L649" class="LineNr">649 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
+<span id="L650" class="LineNr">650 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L651" class="LineNr">651 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎─────────────────────────────────────────────────.</span>
+<span id="L652" class="LineNr">652 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L653" class="LineNr">653 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎get 1234:num, foo:offset                         .</span>
+<span id="L654" class="LineNr">654 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎unknown element 'foo' in container 'number'      .</span>
+<span id="L655" class="LineNr">655 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎first ingredient of 'get' should be a container,↩.</span>
+<span id="L656" class="LineNr">656 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎ but got '1234:num'                              .</span>
+<span id="L657" class="LineNr">657 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L658" class="LineNr">658 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L659" class="LineNr">659 </span>  ]
+<span id="L660" class="LineNr">660 </span>]
+<span id="L661" class="LineNr">661 </span>
+<span id="L662" class="LineNr">662 </span><span class="muScenario">scenario</span> sandbox-can-handle-infinite-loop [
+<span id="L663" class="LineNr">663 </span>  <span class="Constant">local-scope</span>
+<span id="L664" class="LineNr">664 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L665" class="LineNr">665 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">20/height</span>
+<span id="L666" class="LineNr">666 </span>  <span class="Comment"># sandbox editor will trigger an infinite loop</span>
+<span id="L667" class="LineNr">667 </span>  assume-resources [
+<span id="L668" class="LineNr">668 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L669" class="LineNr">669 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
+<span id="L670" class="LineNr">670 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  {|</span>
+<span id="L671" class="LineNr">671 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |    loop|</span>
+<span id="L672" class="LineNr">672 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  }|</span>
+<span id="L673" class="LineNr">673 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]</span>|
+<span id="L674" class="LineNr">674 </span>  <span class="Conceal">¦</span> ]
+<span id="L675" class="LineNr">675 </span>  ]
+<span id="L676" class="LineNr">676 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo]</span>
+<span id="L677" class="LineNr">677 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L678" class="LineNr">678 </span>  <span class="Comment"># run the sandbox</span>
+<span id="L679" class="LineNr">679 </span>  assume-console [
+<span id="L680" class="LineNr">680 </span>  <span class="Conceal">¦</span> press F4
+<span id="L681" class="LineNr">681 </span>  ]
+<span id="L682" class="LineNr">682 </span>  run [
+<span id="L683" class="LineNr">683 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L684" class="LineNr">684 </span>  ]
+<span id="L685" class="LineNr">685 </span>  screen-should-contain [
+<span id="L686" class="LineNr">686 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
+<span id="L687" class="LineNr">687 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
+<span id="L688" class="LineNr">688 </span>  <span class="Conceal">¦</span><span class="Constant"> .  {                                               ╎─────────────────────────────────────────────────.</span>
+<span id="L689" class="LineNr">689 </span>  <span class="Conceal">¦</span><span class="Constant"> .    loop                                          ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L690" class="LineNr">690 </span>  <span class="Conceal">¦</span><span class="Constant"> .  }                                               ╎foo                                              .</span>
+<span id="L691" class="LineNr">691 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎took too long!                                   .</span>
+<span id="L692" class="LineNr">692 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L693" class="LineNr">693 </span>  <span class="Conceal">¦</span><span class="Constant"> .╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╎                                                 .</span>
+<span id="L694" class="LineNr">694 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L695" class="LineNr">695 </span>  ]
+<span id="L696" class="LineNr">696 </span>]
+<span id="L697" class="LineNr">697 </span>
+<span id="L698" class="LineNr">698 </span><span class="muScenario">scenario</span> sandbox-with-errors-shows-trace [
+<span id="L699" class="LineNr">699 </span>  <span class="Constant">local-scope</span>
+<span id="L700" class="LineNr">700 </span>  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+<span id="L701" class="LineNr">701 </span>  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+<span id="L702" class="LineNr">702 </span>  <span class="Comment"># generate a stash and a error</span>
+<span id="L703" class="LineNr">703 </span>  assume-resources [
+<span id="L704" class="LineNr">704 </span>  <span class="Conceal">¦</span> <span class="Constant">[lesson/recipes.mu]</span> <span class="Special">&lt;-</span> [
+<span id="L705" class="LineNr">705 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|recipe</span> foo <span class="Constant">[|</span>
+<span id="L706" class="LineNr">706 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  local-scope|</span>
+<span id="L707" class="LineNr">707 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  a:num &lt;- next-ingredient|</span>
+<span id="L708" class="LineNr">708 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  b:num &lt;- next-ingredient|</span>
+<span id="L709" class="LineNr">709 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |  stash [dividing by]</span>, b|
+<span id="L710" class="LineNr">710 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|</span>  _, c:num <span class="Special">&lt;-</span> divide-with-remainder a, b|
+<span id="L711" class="LineNr">711 </span>  <span class="Conceal">¦</span> <span class="Conceal">¦</span> <span class="Constant">|</span>  <span class="muControl">reply</span> b|
+<span id="L712" class="LineNr">712 </span><span class="Constant">  </span><span class="Conceal">¦</span><span class="Constant"> </span><span class="Conceal">¦</span><span class="Constant"> |]|</span>
+<span id="L713" class="LineNr">713 </span>  <span class="Conceal">¦</span> ]
+<span id="L714" class="LineNr">714 </span>  ]
+<span id="L715" class="LineNr">715 </span>  env:&amp;:environment <span class="Special">&lt;-</span> <a href='004-programming-environment.mu.html#L21'>new-programming-environment</a> <a href='../088file.mu.html#L11'>resources</a>, <a href='../081print.mu.html#L4'>screen</a>, <span class="Constant">[foo 4, 0]</span>
+<span id="L716" class="LineNr">716 </span>  <a href='004-programming-environment.mu.html#L400'>render-all</a> <a href='../081print.mu.html#L4'>screen</a>, env, <a href='001-editor.mu.html#L107'>render</a>
+<span id="L717" class="LineNr">717 </span>  <span class="Comment"># run</span>
+<span id="L718" class="LineNr">718 </span>  assume-console [
+<span id="L719" class="LineNr">719 </span>  <span class="Conceal">¦</span> press F4
+<span id="L720" class="LineNr">720 </span>  ]
+<span id="L721" class="LineNr">721 </span>  <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
+<span id="L722" class="LineNr">722 </span>  <span class="Comment"># screen prints error message</span>
+<span id="L723" class="LineNr">723 </span>  screen-should-contain [
+<span id="L724" class="LineNr">724 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
+<span id="L725" class="LineNr">725 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
+<span id="L726" class="LineNr">726 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L727" class="LineNr">727 </span>  <span class="Conceal">¦</span><span class="Constant"> .  a:num &lt;- next-ingredient                        ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L728" class="LineNr">728 </span>  <span class="Conceal">¦</span><span class="Constant"> .  b:num &lt;- next-ingredient                        ╎foo 4, 0                                         .</span>
+<span id="L729" class="LineNr">729 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [dividing by], b                          ╎foo: divide by zero in '_, c:num &lt;- divide-with-↩.</span>
+<span id="L730" class="LineNr">730 </span>  <span class="Conceal">¦</span><span class="Constant"> .  _, c:num &lt;- divide-with-remainder a, b          ╎remainder a, b'                                  .</span>
+<span id="L731" class="LineNr">731 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply b                                         ╎─────────────────────────────────────────────────.</span>
+<span id="L732" class="LineNr">732 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎                                                 .</span>
+<span id="L733" class="LineNr">733 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎                                                 .</span>
+<span id="L734" class="LineNr">734 </span>  ]
+<span id="L735" class="LineNr">735 </span>  <span class="Comment"># click on the call in the sandbox</span>
+<span id="L736" class="LineNr">736 </span>  assume-console [
+<span id="L737" class="LineNr">737 </span>  <span class="Conceal">¦</span> left-click<span class="Constant"> 4</span>,<span class="Constant"> 55</span>
+<span id="L738" class="LineNr">738 </span>  ]
+<span id="L739" class="LineNr">739 </span>  run [
+<span id="L740" class="LineNr">740 </span>  <span class="Conceal">¦</span> <a href='004-programming-environment.mu.html#L39'>event-loop</a> <a href='../081print.mu.html#L4'>screen</a>, <a href='../084console.mu.html#L23'>console</a>, env, <a href='../088file.mu.html#L11'>resources</a>
 <span id="L741" class="LineNr">741 </span>  ]
-<span id="L742" class="LineNr">742 </span>]
+<span id="L742" class="LineNr">742 </span>  <span class="Comment"># screen should expand trace</span>
+<span id="L743" class="LineNr">743 </span>  screen-should-contain [
+<span id="L744" class="LineNr">744 </span>  <span class="Conceal">¦</span><span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
+<span id="L745" class="LineNr">745 </span>  <span class="Conceal">¦</span><span class="Constant"> .recipe foo [                                      ╎                                                 .</span>
+<span id="L746" class="LineNr">746 </span>  <span class="Conceal">¦</span><span class="Constant"> .  local-scope                                     ╎─────────────────────────────────────────────────.</span>
+<span id="L747" class="LineNr">747 </span>  <span class="Conceal">¦</span><span class="Constant"> .  a:num &lt;- next-ingredient                        ╎0   edit       copy       to recipe    delete    .</span>
+<span id="L748" class="LineNr">748 </span>  <span class="Conceal">¦</span><span class="Constant"> .  b:num &lt;- next-ingredient                        ╎foo 4, 0                                         .</span>
+<span id="L749" class="LineNr">749 </span>  <span class="Conceal">¦</span><span class="Constant"> .  stash [dividing by], b                          ╎dividing by 0                                    .</span>
+<span id="L750" class="LineNr">750 </span>  <span class="Conceal">¦</span><span class="Constant"> .  _, c:num &lt;- divide-with-remainder a, b          ╎14 instructions run                              .</span>
+<span id="L751" class="LineNr">751 </span>  <span class="Conceal">¦</span><span class="Constant"> .  reply b                                         ╎foo: divide by zero in '_, c:num &lt;- divide-with-↩.</span>
+<span id="L752" class="LineNr">752 </span>  <span class="Conceal">¦</span><span class="Constant"> .]                                                 ╎remainder a, b'                                  .</span>
+<span id="L753" class="LineNr">753 </span>  <span class="Conceal">¦</span><span class="Constant"> .                                                  ╎─────────────────────────────────────────────────.</span>
+<span id="L754" class="LineNr">754 </span>  ]
+<span id="L755" class="LineNr">755 </span>]
 </pre>
 </body>
 </html>
diff --git a/sandbox/004-programming-environment.mu b/sandbox/004-programming-environment.mu
index b260a110..9e28a215 100644
--- a/sandbox/004-programming-environment.mu
+++ b/sandbox/004-programming-environment.mu
@@ -249,6 +249,7 @@ scenario backspace-over-text [
   ]
   # sandbox editor contains an instruction without storing outputs
   env:&:environment <- new-programming-environment resources, screen, []
+  render-all screen, env, render
   # run the code in the editors
   assume-console [
     type [a]
diff --git a/sandbox/005-sandbox.mu b/sandbox/005-sandbox.mu
index b0b28ead..3375a60f 100644
--- a/sandbox/005-sandbox.mu
+++ b/sandbox/005-sandbox.mu
@@ -47,6 +47,7 @@ scenario run-and-show-results [
   ]
   # sandbox editor contains an instruction without storing outputs
   env:&:environment <- new-programming-environment resources, screen, [divide-with-remainder 11, 3]
+  render-all screen, env, render
   # run the code in the editors
   assume-console [
     press F4
@@ -521,6 +522,7 @@ scenario run-updates-results [
   ]
   # sandbox editor contains an instruction without storing outputs
   env:&:environment <- new-programming-environment resources, screen, [foo]  # contents of sandbox editor
+  render-all screen, env, render
   # run the code in the editors
   assume-console [
     press F4
@@ -575,6 +577,7 @@ scenario run-instruction-manages-screen-per-sandbox [
   ]
   # sandbox editor contains an instruction
   env:&:environment <- new-programming-environment resources, screen, [print screen, 4]  # contents of sandbox editor
+  render-all screen, env, render
   # run the code in the editor
   assume-console [
     press F4
diff --git a/sandbox/006-sandbox-copy.mu b/sandbox/006-sandbox-copy.mu
index 4835f02e..33e31cc9 100644
--- a/sandbox/006-sandbox-copy.mu
+++ b/sandbox/006-sandbox-copy.mu
@@ -9,6 +9,7 @@ scenario copy-a-sandbox-to-editor [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 1, 1]  # contents of sandbox editor
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -75,6 +76,7 @@ scenario copy-a-sandbox-to-editor-2 [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 1, 1]  # contents of sandbox editor
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -228,6 +230,7 @@ scenario copy-fails-if-sandbox-editor-not-empty [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 1, 1]  # contents of sandbox editor
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
diff --git a/sandbox/007-sandbox-delete.mu b/sandbox/007-sandbox-delete.mu
index 107c861c..955eac8f 100644
--- a/sandbox/007-sandbox-delete.mu
+++ b/sandbox/007-sandbox-delete.mu
@@ -7,6 +7,7 @@ scenario deleting-sandboxes [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, []
+  render-all screen, env, render
   # run a few commands
   assume-console [
     type [divide-with-remainder 11, 3]
diff --git a/sandbox/008-sandbox-edit.mu b/sandbox/008-sandbox-edit.mu
index ec4fd578..aef61619 100644
--- a/sandbox/008-sandbox-edit.mu
+++ b/sandbox/008-sandbox-edit.mu
@@ -8,6 +8,7 @@ scenario clicking-on-sandbox-edit-button-moves-it-to-editor [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 2, 2]
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -60,6 +61,7 @@ scenario clicking-on-sandbox-edit-button-moves-it-to-editor-2 [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [add 2, 2]
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
@@ -162,6 +164,7 @@ scenario sandbox-with-print-can-be-edited [
   ]
   # right editor contains a print instruction
   env:&:environment <- new-programming-environment resources, screen, [print screen, 4]
+  render-all screen, env, render
   # run the sandbox
   assume-console [
     press F4
diff --git a/sandbox/009-sandbox-test.mu b/sandbox/009-sandbox-test.mu
index 1c24bcb8..34fed44e 100644
--- a/sandbox/009-sandbox-test.mu
+++ b/sandbox/009-sandbox-test.mu
@@ -13,6 +13,7 @@ scenario sandbox-click-on-result-toggles-color-to-green [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   # run it
   assume-console [
     press F4
diff --git a/sandbox/010-sandbox-trace.mu b/sandbox/010-sandbox-trace.mu
index 27f2915a..2c4e40cc 100644
--- a/sandbox/010-sandbox-trace.mu
+++ b/sandbox/010-sandbox-trace.mu
@@ -8,6 +8,7 @@ scenario sandbox-click-on-code-toggles-app-trace [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [stash [abc]]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -77,6 +78,7 @@ scenario sandbox-shows-app-trace-and-result [
   test-sandbox:text <- new [stash [abc]
 add 2, 2]
   env:&:environment <- new-programming-environment resources, screen, test-sandbox
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -121,6 +123,7 @@ scenario clicking-on-app-trace-does-nothing [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [stash 123456789]
+  render-all screen, env, render
   # create and expand the trace
   assume-console [
     press F4
diff --git a/sandbox/011-errors.mu b/sandbox/011-errors.mu
index 7c04621d..06a5fb16 100644
--- a/sandbox/011-errors.mu
+++ b/sandbox/011-errors.mu
@@ -163,6 +163,7 @@ scenario run-updates-status-with-first-erroneous-sandbox [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, []
+  render-all screen, env, render
   assume-console [
     # create invalid sandbox 1
     type [get foo, x:offset]
@@ -187,6 +188,7 @@ scenario run-updates-status-with-first-erroneous-sandbox-2 [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, []
+  render-all screen, env, render
   assume-console [
     # create invalid sandbox 2
     type [get foo, x:offset]
@@ -214,6 +216,7 @@ scenario run-hides-errors-from-past-sandboxes [
   assume-resources [
   ]
   env:&:environment <- new-programming-environment resources, screen, [get foo, x:offset]  # invalid
+  render-all screen, env, render
   assume-console [
     press F4  # generate error
   ]
@@ -256,6 +259,7 @@ scenario run-updates-errors-for-shape-shifting-recipes [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo 2]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -307,6 +311,7 @@ scenario run-avoids-spurious-errors-on-reloading-shape-shifting-recipes [
   test-sandbox:text <- new [x:&:list:num <- copy 0
 to-text x]
   env:&:environment <- new-programming-environment resources, screen, test-sandbox
+  render-all screen, env, render
   # run it once
   assume-console [
     press F4
@@ -357,6 +362,7 @@ scenario run-shows-missing-type-errors [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -385,6 +391,7 @@ scenario run-shows-unbalanced-bracket-errors [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -418,6 +425,7 @@ scenario run-shows-get-on-non-container-errors [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -450,6 +458,7 @@ scenario run-shows-non-literal-get-argument-errors [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -481,6 +490,7 @@ scenario run-shows-errors-everytime [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -520,6 +530,7 @@ scenario run-instruction-and-print-errors [
   ]
   # editor contains an illegal instruction
   env:&:environment <- new-programming-environment resources, screen, [get 1:&:point, 1:offset]
+  render-all screen, env, render
   assume-console [
     press F4
   ]
@@ -559,6 +570,7 @@ scenario run-instruction-and-print-errors-only-once [
   ]
   # editor contains an illegal instruction
   env:&:environment <- new-programming-environment resources, screen, [get 1234:num, foo:offset]
+  render-all screen, env, render
   # run the code in the editors multiple times
   assume-console [
     press F4
@@ -593,6 +605,7 @@ scenario sandbox-can-handle-infinite-loop [
 loop
 }]
   env:&:environment <- new-programming-environment resources, screen, test-sandbox
+  render-all screen, env, render
   # run the sandbox
   assume-console [
     press F4
@@ -632,6 +645,7 @@ scenario sandbox-with-errors-shows-trace [
     ]
   ]
   env:&:environment <- new-programming-environment resources, screen, [foo 4, 0]
+  render-all screen, env, render
   # run
   assume-console [
     press F4