2996

12 files changed, 1186 insertions, 812 deletions

diff --git a/html/edit/001-editor.mu.html b/html/edit/001-editor.mu.html
index 62f21806..6118097e 100644
--- a/html/edit/001-editor.mu.html
+++ b/html/edit/001-editor.mu.html
@@ -207,7 +207,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
         before-cursor<span class="Special"> &lt;- </span>prev curr
       <span class="Delimiter">}</span>
       <span class="Comment"># clear rest of line in this window</span>
-      clear-line-delimited screen, column, right
+      clear-line-until screen, right
       <span class="Comment"># skip to next line</span>
       row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
       column<span class="Special"> &lt;- </span>copy left
@@ -257,25 +257,6 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="muControl">return</span> row, column, screen/same-as-ingredient:<span class="Constant">0</span>, editor/same-as-ingredient:<span class="Constant">1</span>
 ]
 
-<span class="muRecipe">def</span> clear-line-delimited screen:address:screen, column:number, right:number<span class="muRecipe"> -&gt; </span>screen:address:screen [
-  <span class="Constant">local-scope</span>
-  <span class="Constant">load-ingredients</span>
-  space:character<span class="Special"> &lt;- </span>copy <span class="Constant">32/space</span>
-  bg-color:number, bg-color-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
-  <span class="Delimiter">{</span>
-    <span class="Comment"># default bg-color to black</span>
-    <span class="muControl">break-if</span> bg-color-found?
-    bg-color<span class="Special"> &lt;- </span>copy <span class="Constant">0/black</span>
-  <span class="Delimiter">}</span>
-  <span class="Delimiter">{</span>
-    done?:boolean<span class="Special"> &lt;- </span>greater-than column, right
-    <span class="muControl">break-if</span> done?
-    screen<span class="Special"> &lt;- </span>print screen, space, <span class="Constant">7/white</span>, bg-color  <span class="Comment"># foreground color is mostly unused except if the cursor shows up at this cell</span>
-    column<span class="Special"> &lt;- </span>add column, <span class="Constant">1</span>
-    <span class="muControl">loop</span>
-  <span class="Delimiter">}</span>
-]
-
 <span class="muRecipe">def</span> clear-screen-from screen:address:screen, row:number, column:number, left:number, right:number<span class="muRecipe"> -&gt; </span>screen:address:screen [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
@@ -287,7 +268,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Delimiter">}</span>
   <span class="Comment"># if not, go the slower route</span>
   screen<span class="Special"> &lt;- </span>move-cursor screen, row, column
-  clear-line-delimited screen, column, right
+  clear-line-until screen, right
   clear-rest-of-screen screen, row, left, right
   <span class="muControl">return</span> screen/same-as-ingredient:<span class="Constant">0</span>
 ]
@@ -302,7 +283,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     at-bottom-of-screen?:boolean<span class="Special"> &lt;- </span>greater-or-equal row, screen-height
     <span class="muControl">break-if</span> at-bottom-of-screen?
     screen<span class="Special"> &lt;- </span>move-cursor screen, row, left
-    clear-line-delimited screen, left, right
+    clear-line-until screen, right
     row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
     <span class="muControl">loop</span>
   <span class="Delimiter">}</span>
diff --git a/html/edit/002-typing.mu.html b/html/edit/002-typing.mu.html
index a9f02220..7375cd90 100644
--- a/html/edit/002-typing.mu.html
+++ b/html/edit/002-typing.mu.html
@@ -308,7 +308,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
   right:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">right:offset</span>
   row:number, column:number<span class="Special"> &lt;- </span>render screen, editor
-  clear-line-delimited screen, column, right
+  clear-line-until screen, right
   row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
   draw-horizontal screen, row, left, right, <span class="Constant">9480/horizontal-dotted</span>
   row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
diff --git a/html/edit/004-programming-environment.mu.html b/html/edit/004-programming-environment.mu.html
index c05d0127..6ae14e6c 100644
--- a/html/edit/004-programming-environment.mu.html
+++ b/html/edit/004-programming-environment.mu.html
@@ -121,6 +121,8 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
       touch-type:number<span class="Special"> &lt;- </span>get t, <span class="Constant">type:offset</span>
       is-left-click?:boolean<span class="Special"> &lt;- </span>equal touch-type, <span class="Constant">65513/mouse-left</span>
       <span class="muControl">loop-unless</span> is-left-click?, <span class="Constant">+next-event:label</span>
+      click-row:number<span class="Special"> &lt;- </span>get t, <span class="Constant">row:offset</span>
+      click-column:number<span class="Special"> &lt;- </span>get t, <span class="Constant">column:offset</span>
       <span class="Comment"># later exceptions for non-editor touches will go here</span>
 <span class="Constant">      &lt;global-touch&gt;</span>
       <span class="Comment"># send to both editors</span>
@@ -446,7 +448,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   left:number<span class="Special"> &lt;- </span>get *recipes, <span class="Constant">left:offset</span>
   right:number<span class="Special"> &lt;- </span>get *recipes, <span class="Constant">right:offset</span>
   row:number, column:number, screen<span class="Special"> &lt;- </span>render screen, recipes
-  clear-line-delimited screen, column, right
+  clear-line-until screen, right
   row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
 <span class="Constant">  &lt;render-recipe-components-end&gt;</span>
   <span class="Comment"># draw dotted line after recipes</span>
@@ -463,7 +465,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   left:number<span class="Special"> &lt;- </span>get *current-sandbox, <span class="Constant">left:offset</span>
   right:number<span class="Special"> &lt;- </span>get *current-sandbox, <span class="Constant">right:offset</span>
   row:number, column:number, screen, current-sandbox<span class="Special"> &lt;- </span>render screen, current-sandbox
-  clear-line-delimited screen, column, right
+  clear-line-until screen, right
   row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
   <span class="Comment"># draw solid line after code (you'll see why in later layers)</span>
   draw-horizontal screen, row, left, right, <span class="Constant">9473/horizontal</span>
@@ -542,7 +544,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     <span class="muControl">loop</span>
   <span class="Delimiter">}</span>
   was-at-left?:boolean<span class="Special"> &lt;- </span>equal column, left
-  clear-line-delimited screen, column, right
+  clear-line-until screen, right
   <span class="Delimiter">{</span>
     <span class="muControl">break-if</span> was-at-left?
     row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
@@ -605,7 +607,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     <span class="muControl">loop</span>
   <span class="Delimiter">}</span>
   was-at-left?:boolean<span class="Special"> &lt;- </span>equal column, left
-  clear-line-delimited screen, column, right
+  clear-line-until screen, right
   <span class="Delimiter">{</span>
     <span class="muControl">break-if</span> was-at-left?
     row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
diff --git a/html/edit/005-sandbox.mu.html b/html/edit/005-sandbox.mu.html
index 660791b8..e3523d27 100644
--- a/html/edit/005-sandbox.mu.html
+++ b/html/edit/005-sandbox.mu.html
@@ -38,6 +38,9 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
 <span class="Comment"># Running code in the sandbox editor prepends its contents to a list of</span>
 <span class="Comment"># (non-editable) sandboxes below the editor, showing the result and a maybe</span>
 <span class="Comment"># few other things.</span>
+<span class="Comment">#</span>
+<span class="Comment"># This layer draws the menubar buttons non-editable sandboxes but they don't</span>
+<span class="Comment"># do anything yet. Later layers implement each button.</span>
 
 <span class="muRecipe">def!</span> main [
   <span class="Constant">local-scope</span>
@@ -93,7 +96,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                 run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊0                                               x.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊divide-with-remainder 11, 3                      .</span>
    <span class="Constant"> .                                                  ┊3                                                .</span>
    <span class="Constant"> .                                                  ┊2                                                .</span>
@@ -115,19 +118,19 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                                    .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊                                                x.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
    <span class="Constant"> .                                                  ┊3                                                .</span>
    <span class="Constant"> .                                                  ┊2                                                .</span>
    <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
-  <span class="Comment"># sandbox title in reverse video</span>
-  screen-should-contain-in-color <span class="Constant">240/dark-grey</span>, [
+  <span class="Comment"># sandbox menu in reverse video</span>
+  screen-should-contain-in-color <span class="Constant">232/black</span>, [
    <span class="Constant"> .                                                                                                    .</span>
    <span class="Constant"> .                                                                                                    .</span>
    <span class="Constant"> .                                                                                                    .</span>
-   <span class="Constant"> .                                                   0                                                .</span>
+   <span class="Constant"> .                                                   0   edit          copy            delete         .</span>
   ]
   <span class="Comment"># run another command</span>
   assume-console [
@@ -143,11 +146,11 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                 run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊0                                               x.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
    <span class="Constant"> .                                                  ┊4                                                .</span>
    <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊1                                               x.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊divide-with-remainder 11, 3                      .</span>
    <span class="Constant"> .                                                  ┊3                                                .</span>
    <span class="Constant"> .                                                  ┊2                                                .</span>
@@ -303,10 +306,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     <span class="Comment"># render sandbox menu</span>
     row<span class="Special"> &lt;- </span>add row, <span class="Constant">1</span>
     screen<span class="Special"> &lt;- </span>move-cursor screen, row, left
-    print screen, idx, <span class="Constant">240/dark-grey</span>
-    clear-line-delimited screen, left, right
-    delete-icon:character<span class="Special"> &lt;- </span>copy <span class="Constant">120/x</span>
-    print screen, delete-icon, <span class="Constant">245/grey</span>
+    screen<span class="Special"> &lt;- </span>render-sandbox-menu screen, idx, left, right
     <span class="Comment"># save menu row so we can detect clicks to it later</span>
     *sandbox<span class="Special"> &lt;- </span>put *sandbox, <span class="Constant">starting-row-on-screen:offset</span>, row
     <span class="Comment"># render sandbox contents</span>
@@ -348,6 +348,46 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   row, screen<span class="Special"> &lt;- </span>render-sandboxes screen, next-sandbox, left, right, row, render-from, next-idx
 ]
 
+<span class="muRecipe">def</span> render-sandbox-menu screen:address:screen, sandbox-index:number, left:number, right:number<span class="muRecipe"> -&gt; </span>screen:address:screen [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  move-cursor-to-column screen, left
+  edit-button-left:number, edit-button-right:number, copy-button-left:number, copy-button-right:number, delete-button-left:number<span class="Special"> &lt;- </span>sandbox-menu-columns left, right
+  print screen, sandbox-index, <span class="Constant">232/dark-grey</span>, <span class="Constant">245/grey</span>
+  start-buttons:number<span class="Special"> &lt;- </span>subtract edit-button-left, <span class="Constant">1</span>
+  clear-line-until screen, start-buttons, <span class="Constant">245/grey</span>
+  print screen, <span class="Constant">[edit]</span>, <span class="Constant">232/black</span>, <span class="Constant">94/background-orange</span>
+  clear-line-until screen, edit-button-right, <span class="Constant">94/background-orange</span>
+  _, col:number<span class="Special"> &lt;- </span>cursor-position screen
+  at-start-of-copy-button?:boolean<span class="Special"> &lt;- </span>equal col, copy-button-left
+  assert at-start-of-copy-button?, <span class="Constant">[aaa]</span>
+  print screen, <span class="Constant">[copy]</span>, <span class="Constant">232/black</span>, <span class="Constant">58/background-green</span>
+  clear-line-until screen, copy-button-right, <span class="Constant">58/background-green</span>
+  _, col:number<span class="Special"> &lt;- </span>cursor-position screen
+  at-start-of-delete-button?:boolean<span class="Special"> &lt;- </span>equal col, delete-button-left
+  assert at-start-of-delete-button?, <span class="Constant">[bbb]</span>
+  print screen, <span class="Constant">[delete]</span>, <span class="Constant">232/black</span>, <span class="Constant">52/background-red</span>
+  clear-line-until screen, right, <span class="Constant">52/background-red</span>
+]
+
+<span class="Comment"># divide up the menu bar for a sandbox into 3 segments, for edit/copy/delete buttons</span>
+<span class="Comment"># delete-button-right == right</span>
+<span class="Comment"># all left/right pairs are inclusive</span>
+<span class="muRecipe">def</span> sandbox-menu-columns left:number, right:number<span class="muRecipe"> -&gt; </span>edit-button-left:number, edit-button-right:number, copy-button-left:number, copy-button-right:number, delete-button-left:number [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  start-buttons:number<span class="Special"> &lt;- </span>add left, <span class="Constant">4/space-for-sandbox-index</span>
+  buttons-space:number<span class="Special"> &lt;- </span>subtract right, start-buttons
+  button-width:number<span class="Special"> &lt;- </span>divide-with-remainder buttons-space, <span class="Constant">3</span>  <span class="Comment"># integer division</span>
+  buttons-wide-enough?:boolean<span class="Special"> &lt;- </span>greater-or-equal button-width, <span class="Constant">8</span>
+  assert buttons-wide-enough?, <span class="Constant">[sandbox must be at least 30 or so characters wide]</span>
+  edit-button-left:number<span class="Special"> &lt;- </span>copy start-buttons
+  copy-button-left:number<span class="Special"> &lt;- </span>add start-buttons, button-width
+  edit-button-right:number<span class="Special"> &lt;- </span>subtract copy-button-left, <span class="Constant">1</span>
+  delete-button-left:number<span class="Special"> &lt;- </span>subtract right, button-width
+  copy-button-right:number<span class="Special"> &lt;- </span>subtract delete-button-left, <span class="Constant">1</span>
+]
+
 <span class="Comment"># assumes programming environment has no sandboxes; restores them from previous session</span>
 <span class="muRecipe">def</span> restore-sandboxes env:address:programming-environment-data<span class="muRecipe"> -&gt; </span>env:address:programming-environment-data [
   <span class="Constant">local-scope</span>
@@ -360,26 +400,23 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     filename:address:array:character<span class="Special"> &lt;- </span>to-text idx
     contents:address:array:character<span class="Special"> &lt;- </span>restore filename
     <span class="muControl">break-unless</span> contents  <span class="Comment"># stop at first error; assuming file didn't exist</span>
+                           <span class="Comment"># todo: handle empty sandbox</span>
     <span class="Comment"># create new sandbox for file</span>
     curr<span class="Special"> &lt;- </span>new <span class="Constant">sandbox-data:type</span>
     *curr<span class="Special"> &lt;- </span>put *curr, <span class="Constant">data:offset</span>, contents
-    <span class="Comment"># restore expected output for sandbox if it exists</span>
+<span class="Constant">    &lt;end-restore-sandbox&gt;</span>
     <span class="Delimiter">{</span>
-      filename<span class="Special"> &lt;- </span>append filename, <span class="Constant">[.out]</span>
-      contents<span class="Special"> &lt;- </span>restore filename
-      <span class="muControl">break-unless</span> contents
-<span class="Constant">      &lt;end-restore-sandbox&gt;</span>
+      <span class="muControl">break-if</span> idx
+      *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">sandbox:offset</span>, curr
     <span class="Delimiter">}</span>
-<span class="Constant">    +continue</span>
-    idx<span class="Special"> &lt;- </span>add idx, <span class="Constant">1</span>
     <span class="Delimiter">{</span>
-      <span class="muControl">break-unless</span> prev
+      <span class="muControl">break-unless</span> idx
       *prev<span class="Special"> &lt;- </span>put *prev, <span class="Constant">next-sandbox:offset</span>, curr
     <span class="Delimiter">}</span>
+    idx<span class="Special"> &lt;- </span>add idx, <span class="Constant">1</span>
     prev<span class="Special"> &lt;- </span>copy curr
     <span class="muControl">loop</span>
   <span class="Delimiter">}</span>
-  *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">sandbox:offset</span>, curr
   <span class="Comment"># update sandbox count</span>
   *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">number-of-sandboxes:offset</span>, idx
 ]
@@ -473,7 +510,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                 run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
    <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .local-scope                                       ┊0                                               x.</span>
+   <span class="Constant"> .local-scope                                       ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .z:number &lt;- add 2, 2                              ┊foo                                              .</span>
    <span class="Constant"> .reply z                                           ┊4                                                .</span>
    <span class="Constant"> .]                                                 ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
@@ -495,7 +532,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                 run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
    <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .local-scope                                       ┊0                                               x.</span>
+   <span class="Constant"> .local-scope                                       ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .z:number &lt;- add 2, 3                              ┊foo                                              .</span>
    <span class="Constant"> .reply z                                           ┊5                                                .</span>
    <span class="Constant"> .]                                                 ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
@@ -524,7 +561,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                 run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊0                                               x.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊print-integer screen, 4                          .</span>
    <span class="Constant"> .                                                  ┊screen:                                          .</span>
    <span class="Constant"> .                                                  ┊  .4                             .               .</span>
@@ -578,7 +615,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
 
 <span class="muScenario">scenario</span> scrolling-down-past-bottom-of-sandbox-editor [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># initialize sandbox side</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
   <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[add 2, 2]</span>
@@ -587,27 +624,19 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   assume-console [
     <span class="Comment"># create a sandbox</span>
     press F4
-    <span class="Comment"># switch to sandbox editor and type in 2 lines</span>
-    press ctrl-n
-    type <span class="Constant">[abc</span>
-<span class="Constant">]</span>
-  ]
-  run [
-    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-    <span class="Constant">4</span>:character/cursor<span class="Special"> &lt;- </span>copy <span class="Constant">9251/␣</span>
-    print screen:address:screen, <span class="Constant">4</span>:character/cursor
   ]
+  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   screen-should-contain [
-   <span class="Constant"> .                              .  # minor: F4 clears menu tooltip in very narrow screens</span>
-   <span class="Constant"> .               ┊abc           .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊␣             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-  ]
-  <span class="Comment"># hit 'down' at bottom of sandbox editor</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+  ]
+  <span class="Comment"># switch to sandbox window and hit 'page-down'</span>
   assume-console [
-    press down-arrow
+    press ctrl-n
+    press page-down
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
@@ -617,44 +646,37 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
   <span class="Comment"># cursor moves to first sandbox</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊␣            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
-  ]
-  <span class="Comment"># hit 'up'</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊␣   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+  ]
+  <span class="Comment"># hit 'page-up'</span>
   assume-console [
-    press up-arrow
+    press page-up
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
     <span class="Constant">4</span>:character/cursor<span class="Special"> &lt;- </span>copy <span class="Constant">9251/␣</span>
     print screen:address:screen, <span class="Constant">4</span>:character/cursor
   ]
-  <span class="Comment"># sandbox editor displays again</span>
+  <span class="Comment"># sandbox editor displays again, cursor is in editor</span>
   screen-should-contain [
-   <span class="Constant"> .                              .  # minor: F4 clears menu tooltip in very narrow screens</span>
-   <span class="Constant"> .               ┊abc           .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊␣             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊␣                                                .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
   ]
 ]
 
-<span class="Comment"># down on sandbox side updates render-from when sandbox editor has cursor at bottom</span>
+<span class="Comment"># page-down on sandbox side updates render-from to scroll sandboxes</span>
 <span class="muRecipe">after</span> <span class="Constant">&lt;global-keypress&gt;</span> [
   <span class="Delimiter">{</span>
     <span class="muControl">break-unless</span> sandbox-in-focus?
-    down?:boolean<span class="Special"> &lt;- </span>equal k, <span class="Constant">65516/down-arrow</span>
-    <span class="muControl">break-unless</span> down?
-    sandbox-bottom:number<span class="Special"> &lt;- </span>get *current-sandbox, <span class="Constant">bottom:offset</span>
-    sandbox-cursor:number<span class="Special"> &lt;- </span>get *current-sandbox, <span class="Constant">cursor-row:offset</span>
-    sandbox-cursor-on-last-line?:boolean<span class="Special"> &lt;- </span>equal sandbox-bottom, sandbox-cursor
-    <span class="muControl">break-unless</span> sandbox-cursor-on-last-line?
+    page-down?:boolean<span class="Special"> &lt;- </span>equal k, <span class="Constant">65518/page-down</span>
+    <span class="muControl">break-unless</span> page-down?
     sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">sandbox:offset</span>
     <span class="muControl">break-unless</span> sandbox
     <span class="Comment"># slide down if possible</span>
@@ -687,12 +709,12 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Delimiter">}</span>
 ]
 
-<span class="Comment"># 'up' on sandbox side is like 'down': updates render-from when necessary</span>
+<span class="Comment"># 'page-up' on sandbox side is like 'page-down': updates render-from when necessary</span>
 <span class="muRecipe">after</span> <span class="Constant">&lt;global-keypress&gt;</span> [
   <span class="Delimiter">{</span>
     <span class="muControl">break-unless</span> sandbox-in-focus?
-    up?:boolean<span class="Special"> &lt;- </span>equal k, <span class="Constant">65517/up-arrow</span>
-    <span class="muControl">break-unless</span> up?
+    page-up?:boolean<span class="Special"> &lt;- </span>equal k, <span class="Constant">65519/page-up</span>
+    <span class="muControl">break-unless</span> page-up?
     render-from:number<span class="Special"> &lt;- </span>get *env, <span class="Constant">render-from:offset</span>
     at-beginning?:boolean<span class="Special"> &lt;- </span>equal render-from, <span class="Constant">-1</span>
     <span class="muControl">break-if</span> at-beginning?
@@ -726,7 +748,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
 
 <span class="muScenario">scenario</span> scrolling-down-on-recipe-side [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># initialize sandbox side and create a sandbox</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
 <span class="Constant">]</span>
@@ -749,20 +771,17 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   ]
   <span class="Comment"># cursor moves down on recipe side</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊              .</span>
-   <span class="Constant"> .␣              ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .␣                                                 ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
   ]
 ]
 
 <span class="muScenario">scenario</span> scrolling-through-multiple-sandboxes [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># initialize environment</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
   <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
@@ -780,20 +799,20 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Constant">4</span>:character/cursor<span class="Special"> &lt;- </span>copy <span class="Constant">9251/␣</span>
   print screen:address:screen, <span class="Constant">4</span>:character/cursor
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊␣             .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-  ]
-  <span class="Comment"># hit 'down'</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊␣                                                .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+  ]
+  <span class="Comment"># hit 'page-down'</span>
   assume-console [
-    press down-arrow
+    press page-down
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
@@ -803,76 +822,72 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
   <span class="Comment"># cursor moves to first sandbox</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊␣            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-  ]
-  <span class="Comment"># hit 'down' again</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊␣   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+  ]
+  <span class="Comment"># hit 'page-down' again</span>
   assume-console [
-    press down-arrow
+    press page-down
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># just second sandbox displayed</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
-   <span class="Constant"> .               ┊              .</span>
-  ]
-  <span class="Comment"># hit 'down' again</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># hit 'page-down' again</span>
   assume-console [
-    press down-arrow
+    press page-down
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># no change</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
-   <span class="Constant"> .               ┊              .</span>
-  ]
-  <span class="Comment"># hit 'up'</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># hit 'page-up'</span>
   assume-console [
-    press up-arrow
+    press page-up
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># back to displaying both sandboxes without editor</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-  ]
-  <span class="Comment"># hit 'up' again</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+  ]
+  <span class="Comment"># hit 'page-up' again</span>
   assume-console [
-    press up-arrow
+    press page-up
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
@@ -881,42 +896,44 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   ]
   <span class="Comment"># back to displaying both sandboxes as well as editor</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊␣             .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-  ]
-  <span class="Comment"># hit 'up' again</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊␣                                                .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+  ]
+  <span class="Comment"># hit 'page-up' again</span>
   assume-console [
-    press up-arrow
+    press page-up
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+    <span class="Constant">4</span>:character/cursor<span class="Special"> &lt;- </span>copy <span class="Constant">9251/␣</span>
+    print screen:address:screen, <span class="Constant">4</span>:character/cursor
   ]
   <span class="Comment"># no change</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊␣             .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊␣                                                .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
   ]
 ]
 
 <span class="muScenario">scenario</span> scrolling-manages-sandbox-index-correctly [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># initialize environment</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
   <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
@@ -930,18 +947,18 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   ]
   event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊              .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
-  ]
-  <span class="Comment"># hit 'down' and 'up' a couple of times. sandbox index should be stable</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># hit 'page-down' and 'page-up' a couple of times. sandbox index should be stable</span>
   assume-console [
-    press down-arrow
+    press page-down
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
@@ -949,35 +966,35 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
   <span class="Comment"># cursor moves to first sandbox</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
-  ]
-  <span class="Comment"># hit 'up' again</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># hit 'page-up' again</span>
   assume-console [
-    press up-arrow
+    press page-up
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># back to displaying both sandboxes as well as editor</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊              .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
-  ]
-  <span class="Comment"># hit 'down'</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># hit 'page-down'</span>
   assume-console [
-    press down-arrow
+    press page-down
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
@@ -985,13 +1002,13 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Comment"># sandbox editor hidden; first sandbox displayed</span>
   <span class="Comment"># cursor moves to first sandbox</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0            x.  # no change</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
 ]
 </pre>
diff --git a/html/edit/006-sandbox-copy.mu.html b/html/edit/006-sandbox-copy.mu.html
new file mode 100644
index 00000000..c201b609
--- /dev/null
+++ b/html/edit/006-sandbox-copy.mu.html
@@ -0,0 +1,322 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
+<html>
+<head>
+<meta http-equiv="content-type" content="text/html; charset=UTF-8">
+<title>Mu - edit/006-sandbox-copy.mu</title>
+<meta name="Generator" content="Vim/7.4">
+<meta name="plugin-version" content="vim7.4_v2">
+<meta name="syntax" content="none">
+<meta name="settings" content="use_css,pre_wrap,no_foldcolumn,expand_tabs,prevent_copy=">
+<meta name="colorscheme" content="minimal">
+<style type="text/css">
+<!--
+pre { white-space: pre-wrap; font-family: monospace; color: #eeeeee; background-color: #080808; }
+body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color: #080808; }
+* { font-size: 12pt; font-size: 1em; }
+.muScenario { color: #00af00; }
+.Special { color: #c00000; }
+.Delimiter { color: #800080; }
+.muRecipe { color: #ff8700; }
+.Comment { color: #9090ff; }
+.Constant { color: #00a0a0; }
+.SalientComment { color: #00ffff; }
+.muControl { color: #c0a020; }
+-->
+</style>
+
+<script type='text/javascript'>
+<!--
+
+-->
+</script>
+</head>
+<body>
+<pre id='vimCodeElement'>
+<span class="SalientComment">## the 'copy' button makes it easy to duplicate a sandbox, and thence to</span>
+<span class="SalientComment">## see code operate in multiple situations</span>
+
+<span class="muScenario">scenario</span> copy-a-sandbox-to-editor [
+  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+  <span class="Comment"># basic recipe</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
+<span class="Constant">recipe foo [</span>
+<span class="Constant">  reply 4</span>
+<span class="Constant">]</span>]
+  <span class="Comment"># run it</span>
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[foo]</span>
+  assume-console [
+    press F4
+  ]
+  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
+  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># click at left edge of 'copy' button</span>
+  assume-console [
+    left-click <span class="Constant">3</span>, <span class="Constant">69</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  <span class="Comment"># it copies into editor</span>
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊foo                                              .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># cursor should be in the right place</span>
+  assume-console [
+    type <span class="Constant">[0]</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊0foo                                             .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+]
+
+<span class="muScenario">scenario</span> copy-a-sandbox-to-editor-2 [
+  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+  <span class="Comment"># basic recipe</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
+<span class="Constant">recipe foo [</span>
+<span class="Constant">  reply 4</span>
+<span class="Constant">]</span>]
+  <span class="Comment"># run it</span>
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[foo]</span>
+  assume-console [
+    press F4
+  ]
+  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
+  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># click at right edge of 'copy' button (just before 'delete')</span>
+  assume-console [
+    left-click <span class="Constant">3</span>, <span class="Constant">84</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  <span class="Comment"># it copies into editor</span>
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊foo                                              .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># cursor should be in the right place</span>
+  assume-console [
+    type <span class="Constant">[0]</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊0foo                                             .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+]
+
+<span class="muRecipe">after</span> <span class="Constant">&lt;global-touch&gt;</span> [
+  <span class="Comment"># support 'copy' button</span>
+  <span class="Delimiter">{</span>
+    copy?:boolean<span class="Special"> &lt;- </span>should-attempt-copy? click-row, click-column, env
+    <span class="muControl">break-unless</span> copy?
+    copy?, env<span class="Special"> &lt;- </span>try-copy-sandbox click-row, env
+    <span class="muControl">break-unless</span> copy?
+    hide-screen screen
+    screen<span class="Special"> &lt;- </span>render-sandbox-side screen, env
+    screen<span class="Special"> &lt;- </span>update-cursor screen, recipes, current-sandbox, sandbox-in-focus?, env
+    show-screen screen
+    <span class="muControl">loop</span> <span class="Constant">+next-event:label</span>
+  <span class="Delimiter">}</span>
+]
+
+<span class="Comment"># some preconditions for attempting to copy a sandbox</span>
+<span class="muRecipe">def</span> should-attempt-copy? click-row:number, click-column:number, env:address:programming-environment-data<span class="muRecipe"> -&gt; </span>result:boolean [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  <span class="Comment"># are we below the sandbox editor?</span>
+  click-sandbox-area?:boolean<span class="Special"> &lt;- </span>click-on-sandbox-area? click-row, click-column, env
+  <span class="muControl">reply-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
+  <span class="Comment"># narrower, is the click in the columns spanning the 'copy' button?</span>
+  first-sandbox:address:editor-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">current-sandbox:offset</span>
+  assert first-sandbox, <span class="Constant">[!!]</span>
+  sandbox-left-margin:number<span class="Special"> &lt;- </span>get *first-sandbox, <span class="Constant">left:offset</span>
+  sandbox-right-margin:number<span class="Special"> &lt;- </span>get *first-sandbox, <span class="Constant">right:offset</span>
+  _, _, copy-button-left:number, copy-button-right:number, _<span class="Special"> &lt;- </span>sandbox-menu-columns sandbox-left-margin, sandbox-right-margin
+  copy-button-vertical-area?:boolean<span class="Special"> &lt;- </span>within-range? click-column, copy-button-left, copy-button-right
+  <span class="muControl">reply-unless</span> copy-button-vertical-area?, <span class="Constant">0/false</span>
+  <span class="Comment"># finally, is sandbox editor empty?</span>
+  current-sandbox:address:editor-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">current-sandbox:offset</span>
+  result<span class="Special"> &lt;- </span>empty-editor? current-sandbox
+]
+
+<span class="muRecipe">def</span> try-copy-sandbox click-row:number, env:address:programming-environment-data<span class="muRecipe"> -&gt; </span>clicked-on-copy-button?:boolean, env:address:programming-environment-data [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  <span class="Comment"># identify the sandbox to copy, if the click was actually on the 'copy' button</span>
+  sandbox:address:sandbox-data<span class="Special"> &lt;- </span>find-sandbox env, click-row
+  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
+  clicked-on-copy-button?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
+  text:address:array:character<span class="Special"> &lt;- </span>get *sandbox, <span class="Constant">data:offset</span>
+  current-sandbox:address:editor-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">current-sandbox:offset</span>
+  current-sandbox<span class="Special"> &lt;- </span>insert-text current-sandbox, text
+  <span class="Comment"># reset scroll</span>
+  *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">render-from:offset</span>, <span class="Constant">-1</span>
+  <span class="Comment"># position cursor in sandbox editor</span>
+  *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">sandbox-in-focus?:offset</span>, <span class="Constant">1/true</span>
+]
+
+<span class="muRecipe">def</span> find-sandbox env:address:programming-environment-data, click-row:number<span class="muRecipe"> -&gt; </span>result:address:sandbox-data [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  curr-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">sandbox:offset</span>
+  <span class="Delimiter">{</span>
+    start:number<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+    found?:boolean<span class="Special"> &lt;- </span>equal click-row, start
+    <span class="muControl">return-if</span> found?, curr-sandbox
+    curr-sandbox<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
+    <span class="muControl">loop</span>
+  <span class="Delimiter">}</span>
+  <span class="muControl">return</span> <span class="Constant">0/not-found</span>
+]
+
+<span class="muRecipe">def</span> click-on-sandbox-area? click-row:number, click-column:number, env:address:programming-environment-data<span class="muRecipe"> -&gt; </span>result:boolean [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  current-sandbox:address:editor-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">current-sandbox:offset</span>
+  sandbox-left-margin:number<span class="Special"> &lt;- </span>get *current-sandbox, <span class="Constant">left:offset</span>
+  on-sandbox-side?:boolean<span class="Special"> &lt;- </span>greater-or-equal click-column, sandbox-left-margin
+  <span class="muControl">return-unless</span> on-sandbox-side?, <span class="Constant">0/false</span>
+  first-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">sandbox:offset</span>
+  <span class="muControl">return-unless</span> first-sandbox, <span class="Constant">0/false</span>
+  first-sandbox-begins:number<span class="Special"> &lt;- </span>get *first-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
+  result<span class="Special"> &lt;- </span>greater-or-equal click-row, first-sandbox-begins
+]
+
+<span class="muRecipe">def</span> empty-editor? editor:address:editor-data<span class="muRecipe"> -&gt; </span>result:boolean [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  head:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
+  first:address:duplex-list:character<span class="Special"> &lt;- </span>next head
+  result<span class="Special"> &lt;- </span>not first
+]
+
+<span class="muRecipe">def</span> within-range? x:number, low:number, high:number<span class="muRecipe"> -&gt; </span>result:boolean [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  not-too-far-left?:boolean<span class="Special"> &lt;- </span>greater-or-equal x, low
+  not-too-far-right?:boolean<span class="Special"> &lt;- </span>lesser-or-equal x, high
+  result<span class="Special"> &lt;- </span>and not-too-far-left? not-too-far-right?
+]
+
+<span class="muScenario">scenario</span> copy-fails-if-sandbox-editor-not-empty [
+  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+  <span class="Comment"># basic recipe</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
+<span class="Constant">recipe foo [</span>
+<span class="Constant">  reply 4</span>
+<span class="Constant">]</span>]
+  <span class="Comment"># run it</span>
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[foo]</span>
+  assume-console [
+    press F4
+  ]
+  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
+  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># type something into the sandbox editor, then click on the 'copy' button</span>
+  assume-console [
+    left-click <span class="Constant">2</span>, <span class="Constant">70</span>  <span class="Comment"># put cursor in sandbox editor</span>
+    type <span class="Constant">[0]</span>  <span class="Comment"># type something</span>
+    left-click <span class="Constant">3</span>, <span class="Constant">70</span>  <span class="Comment"># click 'copy' button</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  <span class="Comment"># copy doesn't happen</span>
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊0                                                .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># cursor should be in the right place</span>
+  assume-console [
+    type <span class="Constant">[1]</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊01                                               .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+]
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->
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-<title>Mu - edit/006-sandbox-edit.mu</title>
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-* { font-size: 12pt; font-size: 1em; }
-.muScenario { color: #00af00; }
-.Special { color: #c00000; }
-.Delimiter { color: #800080; }
-.muRecipe { color: #ff8700; }
-.Comment { color: #9090ff; }
-.Constant { color: #00a0a0; }
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-<pre id='vimCodeElement'>
-<span class="SalientComment">## editing sandboxes after they've been created</span>
-
-<span class="muScenario">scenario</span> clicking-on-a-sandbox-moves-it-to-editor [
-  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">40/width</span>, <span class="Constant">10/height</span>
-  <span class="Comment"># basic recipe</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
-<span class="Constant">recipe foo [</span>
-<span class="Constant">  reply 4</span>
-<span class="Constant">]</span>]
-  <span class="Comment"># run it</span>
-  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[foo]</span>
-  assume-console [
-    press F4
-  ]
-  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
-  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  reply 4           ┊0                 x.</span>
-   <span class="Constant"> .]                   ┊foo                .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                  .</span>
-   <span class="Constant"> .                    ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                   .</span>
-  ]
-  <span class="Comment"># click somewhere in the first row of the sandbox</span>
-  assume-console [
-    left-click <span class="Constant">3</span>, <span class="Constant">30</span>
-  ]
-  run [
-    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  ]
-  <span class="Comment"># it pops back into editor</span>
-  screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .                    ┊foo                .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  reply 4           ┊                   .</span>
-   <span class="Constant"> .]                   ┊                   .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                   .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-  ]
-  <span class="Comment"># cursor should be in the right place</span>
-  assume-console [
-    type <span class="Constant">[0]</span>
-  ]
-  run [
-    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  ]
-  screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .                    ┊0foo               .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  reply 4           ┊                   .</span>
-   <span class="Constant"> .]                   ┊                   .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                   .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-  ]
-]
-
-<span class="muRecipe">after</span> <span class="Constant">&lt;global-touch&gt;</span> [
-  <span class="Comment"># below sandbox editor? pop appropriate sandbox contents back into sandbox editor</span>
-  <span class="Delimiter">{</span>
-    sandbox-left-margin:number<span class="Special"> &lt;- </span>get *current-sandbox, <span class="Constant">left:offset</span>
-    click-column:number<span class="Special"> &lt;- </span>get t, <span class="Constant">column:offset</span>
-    on-sandbox-side?:boolean<span class="Special"> &lt;- </span>greater-or-equal click-column, sandbox-left-margin
-    <span class="muControl">break-unless</span> on-sandbox-side?
-    first-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">sandbox:offset</span>
-    <span class="muControl">break-unless</span> first-sandbox
-    first-sandbox-begins:number<span class="Special"> &lt;- </span>get *first-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-    click-row:number<span class="Special"> &lt;- </span>get t, <span class="Constant">row:offset</span>
-    below-sandbox-editor?:boolean<span class="Special"> &lt;- </span>greater-or-equal click-row, first-sandbox-begins
-    <span class="muControl">break-unless</span> below-sandbox-editor?
-    empty-sandbox-editor?:boolean<span class="Special"> &lt;- </span>empty-editor? current-sandbox
-    <span class="muControl">break-unless</span> empty-sandbox-editor?  <span class="Comment"># don't clobber existing contents</span>
-    <span class="Comment"># identify the sandbox to edit and remove it from the sandbox list</span>
-    sandbox:address:sandbox-data<span class="Special"> &lt;- </span>extract-sandbox env, click-row
-    <span class="muControl">break-unless</span> sandbox
-    text:address:array:character<span class="Special"> &lt;- </span>get *sandbox, <span class="Constant">data:offset</span>
-    current-sandbox<span class="Special"> &lt;- </span>insert-text current-sandbox, text
-    *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">render-from:offset</span>, <span class="Constant">-1</span>
-    hide-screen screen
-    screen<span class="Special"> &lt;- </span>render-sandbox-side screen, env
-    screen<span class="Special"> &lt;- </span>update-cursor screen, recipes, current-sandbox, sandbox-in-focus?, env
-    show-screen screen
-    <span class="muControl">loop</span> <span class="Constant">+next-event:label</span>
-  <span class="Delimiter">}</span>
-]
-
-<span class="muRecipe">def</span> empty-editor? editor:address:editor-data<span class="muRecipe"> -&gt; </span>result:boolean [
-  <span class="Constant">local-scope</span>
-  <span class="Constant">load-ingredients</span>
-  head:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
-  first:address:duplex-list:character<span class="Special"> &lt;- </span>next head
-  result<span class="Special"> &lt;- </span>not first
-]
-
-<span class="muRecipe">def</span> extract-sandbox env:address:programming-environment-data, click-row:number<span class="muRecipe"> -&gt; </span>result:address:sandbox-data, env:address:programming-environment-data [
-  <span class="Constant">local-scope</span>
-  <span class="Constant">load-ingredients</span>
-  curr-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">sandbox:offset</span>
-  start:number<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-  in-editor?:boolean<span class="Special"> &lt;- </span>lesser-than click-row, start
-  <span class="muControl">return-if</span> in-editor?, <span class="Constant">0</span>
-  first-sandbox?:boolean<span class="Special"> &lt;- </span>equal click-row, start
-  <span class="Delimiter">{</span>
-    <span class="Comment"># first sandbox? pop</span>
-    <span class="muControl">break-unless</span> first-sandbox?
-    next-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
-    *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">sandbox:offset</span>, next-sandbox
-  <span class="Delimiter">}</span>
-  <span class="Delimiter">{</span>
-    <span class="Comment"># not first sandbox?</span>
-    <span class="muControl">break-if</span> first-sandbox?
-    prev-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>copy curr-sandbox
-    curr-sandbox<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
-    <span class="Delimiter">{</span>
-      next-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
-      <span class="muControl">break-unless</span> next-sandbox
-      <span class="Comment"># if click-row &lt; sandbox.next-sandbox.starting-row-on-screen, break</span>
-      next-start:number<span class="Special"> &lt;- </span>get *next-sandbox, <span class="Constant">starting-row-on-screen:offset</span>
-      found?:boolean<span class="Special"> &lt;- </span>lesser-than click-row, next-start
-      <span class="muControl">break-if</span> found?
-      prev-sandbox<span class="Special"> &lt;- </span>copy curr-sandbox
-      curr-sandbox<span class="Special"> &lt;- </span>copy next-sandbox
-      <span class="muControl">loop</span>
-    <span class="Delimiter">}</span>
-    <span class="Comment"># snip sandbox out of its list</span>
-    *prev-sandbox<span class="Special"> &lt;- </span>put *prev-sandbox, <span class="Constant">next-sandbox:offset</span>, next-sandbox
-  <span class="Delimiter">}</span>
-  result<span class="Special"> &lt;- </span>copy curr-sandbox
-  <span class="Comment"># update sandbox count</span>
-  sandbox-count:number<span class="Special"> &lt;- </span>get *env, <span class="Constant">number-of-sandboxes:offset</span>
-  sandbox-count<span class="Special"> &lt;- </span>subtract sandbox-count, <span class="Constant">1</span>
-  *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">number-of-sandboxes:offset</span>, sandbox-count
-  <span class="Comment"># position cursor in sandbox editor</span>
-  *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">sandbox-in-focus?:offset</span>, <span class="Constant">1/true</span>
-]
-
-<span class="muScenario">scenario</span> sandbox-with-print-can-be-edited [
-  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">100/width</span>, <span class="Constant">20/height</span>
-  <span class="Comment"># left editor is empty</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
-  <span class="Comment"># right editor contains an instruction</span>
-  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[print-integer screen, 4]</span>
-  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
-  <span class="Comment"># run the sandbox</span>
-  assume-console [
-    press F4
-  ]
-  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  screen-should-contain [
-   <span class="Constant"> .                                                                                 run (F4)           .</span>
-   <span class="Constant"> .                                                  ┊                                                 .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊0                                               x.</span>
-   <span class="Constant"> .                                                  ┊print-integer screen, 4                          .</span>
-   <span class="Constant"> .                                                  ┊screen:                                          .</span>
-   <span class="Constant"> .                                                  ┊  .4                             .               .</span>
-   <span class="Constant"> .                                                  ┊  .                              .               .</span>
-   <span class="Constant"> .                                                  ┊  .                              .               .</span>
-   <span class="Constant"> .                                                  ┊  .                              .               .</span>
-   <span class="Constant"> .                                                  ┊  .                              .               .</span>
-   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊                                                 .</span>
-  ]
-  <span class="Comment"># edit the sandbox</span>
-  assume-console [
-    left-click <span class="Constant">3</span>, <span class="Constant">70</span>
-  ]
-  run [
-    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  ]
-  screen-should-contain [
-   <span class="Constant"> .                                                                                 run (F4)           .</span>
-   <span class="Constant"> .                                                  ┊print-integer screen, 4                          .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊                                                 .</span>
-   <span class="Constant"> .                                                  ┊                                                 .</span>
-  ]
-]
-
-<span class="muScenario">scenario</span> editing-sandbox-after-scrolling-resets-scroll [
-  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
-  <span class="Comment"># initialize environment</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
-  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
-  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
-  render-all screen, <span class="Constant">3</span>:address:programming-environment-data
-  <span class="Comment"># create 2 sandboxes and scroll to second</span>
-  assume-console [
-    press ctrl-n
-    type <span class="Constant">[add 2, 2]</span>
-    press F4
-    type <span class="Constant">[add 1, 1]</span>
-    press F4
-    press down-arrow
-    press down-arrow
-  ]
-  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
-  ]
-  <span class="Comment"># edit the second sandbox</span>
-  assume-console [
-    left-click <span class="Constant">2</span>, <span class="Constant">20</span>
-  ]
-  run [
-    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  ]
-  <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
-  screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
-  ]
-]
-
-<span class="muScenario">scenario</span> editing-sandbox-updates-sandbox-count [
-  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
-  <span class="Comment"># initialize environment</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
-  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
-  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
-  render-all screen, <span class="Constant">3</span>:address:programming-environment-data
-  <span class="Comment"># create 2 sandboxes</span>
-  assume-console [
-    press ctrl-n
-    type <span class="Constant">[add 2, 2]</span>
-    press F4
-    type <span class="Constant">[add 1, 1]</span>
-    press F4
-  ]
-  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊              .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
-  ]
-  <span class="Comment"># edit the second sandbox, then resave</span>
-  assume-console [
-    left-click <span class="Constant">3</span>, <span class="Constant">20</span>
-    press F4
-  ]
-  run [
-    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  ]
-  <span class="Comment"># no change in contents</span>
-  screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊              .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
-  ]
-  <span class="Comment"># now try to scroll past end</span>
-  assume-console [
-    press down-arrow
-    press down-arrow
-    press down-arrow
-  ]
-  run [
-    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
-  ]
-  <span class="Comment"># screen should show just final sandbox</span>
-  screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
-  ]
-]
-</pre>
-</body>
-</html>
-<!-- vim: set foldmethod=manual : -->
diff --git a/html/edit/007-sandbox-delete.mu.html b/html/edit/007-sandbox-delete.mu.html
index b29c649d..137a7887 100644
--- a/html/edit/007-sandbox-delete.mu.html
+++ b/html/edit/007-sandbox-delete.mu.html
@@ -53,20 +53,20 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                 run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊0                                               x.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
    <span class="Constant"> .                                                  ┊4                                                .</span>
    <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊1                                               x.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊divide-with-remainder 11, 3                      .</span>
    <span class="Constant"> .                                                  ┊3                                                .</span>
    <span class="Constant"> .                                                  ┊2                                                .</span>
    <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
-  <span class="Comment"># delete second sandbox</span>
+  <span class="Comment"># delete second sandbox by clicking on left edge of 'delete' button</span>
   assume-console [
-    left-click <span class="Constant">7</span>, <span class="Constant">99</span>
+    left-click <span class="Constant">7</span>, <span class="Constant">85</span>
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
@@ -75,14 +75,14 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                 run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊0                                               x.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
    <span class="Constant"> .                                                  ┊4                                                .</span>
    <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
-  <span class="Comment"># delete first sandbox</span>
+  <span class="Comment"># delete first sandbox by clicking at right edge of 'delete' button</span>
   assume-console [
     left-click <span class="Constant">3</span>, <span class="Constant">99</span>
   ]
@@ -99,10 +99,12 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
 ]
 
 <span class="muRecipe">after</span> <span class="Constant">&lt;global-touch&gt;</span> [
-  <span class="Comment"># on a sandbox delete icon? process delete</span>
+  <span class="Comment"># support 'delete' button</span>
   <span class="Delimiter">{</span>
-    was-delete?:boolean<span class="Special"> &lt;- </span>delete-sandbox t, env
-    <span class="muControl">break-unless</span> was-delete?
+    delete?:boolean<span class="Special"> &lt;- </span>should-attempt-delete? click-row, click-column, env
+    <span class="muControl">break-unless</span> delete?
+    delete?, env<span class="Special"> &lt;- </span>try-delete-sandbox click-row, env
+    <span class="muControl">break-unless</span> delete?
     hide-screen screen
     screen<span class="Special"> &lt;- </span>render-sandbox-side screen, env
     screen<span class="Special"> &lt;- </span>update-cursor screen, recipes, current-sandbox, sandbox-in-focus?, env
@@ -111,70 +113,77 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">def</span> delete-sandbox t:touch-event, env:address:programming-environment-data<span class="muRecipe"> -&gt; </span>was-delete?:boolean, env:address:programming-environment-data [
+<span class="Comment"># some preconditions for attempting to delete a sandbox</span>
+<span class="muRecipe">def</span> should-attempt-delete? click-row:number, click-column:number, env:address:programming-environment-data<span class="muRecipe"> -&gt; </span>result:boolean [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
-  click-column:number<span class="Special"> &lt;- </span>get t, <span class="Constant">column:offset</span>
-  current-sandbox:address:editor-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">current-sandbox:offset</span>
-  right:number<span class="Special"> &lt;- </span>get *current-sandbox, <span class="Constant">right:offset</span>
-  at-right?:boolean<span class="Special"> &lt;- </span>equal click-column, right
-  <span class="muControl">return-unless</span> at-right?, <span class="Constant">0/false</span>
-  click-row:number<span class="Special"> &lt;- </span>get t, <span class="Constant">row:offset</span>
+  <span class="Comment"># are we below the sandbox editor?</span>
+  click-sandbox-area?:boolean<span class="Special"> &lt;- </span>click-on-sandbox-area? click-row, click-column, env
+  <span class="muControl">reply-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
+  <span class="Comment"># narrower, is the click in the columns spanning the 'copy' button?</span>
+  first-sandbox:address:editor-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">current-sandbox:offset</span>
+  assert first-sandbox, <span class="Constant">[!!]</span>
+  sandbox-left-margin:number<span class="Special"> &lt;- </span>get *first-sandbox, <span class="Constant">left:offset</span>
+  sandbox-right-margin:number<span class="Special"> &lt;- </span>get *first-sandbox, <span class="Constant">right:offset</span>
+  _, _, _, _, delete-button-left:number<span class="Special"> &lt;- </span>sandbox-menu-columns sandbox-left-margin, sandbox-right-margin
+  result<span class="Special"> &lt;- </span>within-range? click-column, delete-button-left, sandbox-right-margin
+]
+
+<span class="muRecipe">def</span> try-delete-sandbox click-row:number, env:address:programming-environment-data<span class="muRecipe"> -&gt; </span>clicked-on-delete-button?:boolean, env:address:programming-environment-data [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  <span class="Comment"># identify the sandbox to delete, if the click was actually on the 'delete' button</span>
+  sandbox:address:sandbox-data<span class="Special"> &lt;- </span>find-sandbox env, click-row
+  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
+  clicked-on-delete-button?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
+  env<span class="Special"> &lt;- </span>delete-sandbox env, sandbox
+]
+
+<span class="muRecipe">def</span> delete-sandbox env:address:programming-environment-data, sandbox:address:sandbox-data<span class="muRecipe"> -&gt; </span>env:address:programming-environment-data [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  curr-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">sandbox:offset</span>
+  first-sandbox?:boolean<span class="Special"> &lt;- </span>equal curr-sandbox, sandbox
   <span class="Delimiter">{</span>
-    first:address:sandbox-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">sandbox:offset</span>
-    <span class="muControl">reply-unless</span> first, <span class="Constant">0/false</span>
-    target-row:number<span class="Special"> &lt;- </span>get *first, <span class="Constant">starting-row-on-screen:offset</span>
-    delete-first?:boolean<span class="Special"> &lt;- </span>equal target-row, click-row
-    <span class="muControl">break-unless</span> delete-first?
-    new-first:address:sandbox-data<span class="Special"> &lt;- </span>get *first, <span class="Constant">next-sandbox:offset</span>
-    *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">sandbox:offset</span>, new-first
-    env<span class="Special"> &lt;- </span>fixup-delete env, new-first
-    <span class="muControl">return</span> <span class="Constant">1/true</span>  <span class="Comment"># force rerender</span>
+    <span class="Comment"># first sandbox? pop</span>
+    <span class="muControl">break-unless</span> first-sandbox?
+    next-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
+    *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">sandbox:offset</span>, next-sandbox
   <span class="Delimiter">}</span>
-  prev:address:sandbox-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">sandbox:offset</span>
-  assert prev, <span class="Constant">[failed to find any sandboxes!]</span>
-  curr:address:sandbox-data<span class="Special"> &lt;- </span>get *prev, <span class="Constant">next-sandbox:offset</span>
   <span class="Delimiter">{</span>
-    <span class="muControl">break-unless</span> curr
-    <span class="Comment"># more sandboxes to check</span>
+    <span class="Comment"># not first sandbox?</span>
+    <span class="muControl">break-if</span> first-sandbox?
+    prev-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>copy curr-sandbox
+    curr-sandbox<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
     <span class="Delimiter">{</span>
-      target-row:number<span class="Special"> &lt;- </span>get *curr, <span class="Constant">starting-row-on-screen:offset</span>
-      delete-curr?:boolean<span class="Special"> &lt;- </span>equal target-row, click-row
-      <span class="muControl">break-unless</span> delete-curr?
-      <span class="Comment"># delete this sandbox</span>
-      next:address:sandbox-data<span class="Special"> &lt;- </span>get *curr, <span class="Constant">next-sandbox:offset</span>
-      *prev<span class="Special"> &lt;- </span>put *prev, <span class="Constant">next-sandbox:offset</span>, next
-      env<span class="Special"> &lt;- </span>fixup-delete env, next
-      <span class="muControl">return</span> <span class="Constant">1/true</span>  <span class="Comment"># force rerender</span>
+      assert curr-sandbox, <span class="Constant">[sandbox not found! something is wrong.]</span>
+      found?:boolean<span class="Special"> &lt;- </span>equal curr-sandbox, sandbox
+      <span class="muControl">break-if</span> found?
+      prev-sandbox<span class="Special"> &lt;- </span>copy curr-sandbox
+      curr-sandbox<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
+      <span class="muControl">loop</span>
     <span class="Delimiter">}</span>
-    prev<span class="Special"> &lt;- </span>copy curr
-    curr<span class="Special"> &lt;- </span>get *curr, <span class="Constant">next-sandbox:offset</span>
-    <span class="muControl">loop</span>
+    <span class="Comment"># snip sandbox out of its list</span>
+    next-sandbox:address:sandbox-data<span class="Special"> &lt;- </span>get *curr-sandbox, <span class="Constant">next-sandbox:offset</span>
+    *prev-sandbox<span class="Special"> &lt;- </span>put *prev-sandbox, <span class="Constant">next-sandbox:offset</span>, next-sandbox
   <span class="Delimiter">}</span>
-  <span class="muControl">return</span> <span class="Constant">0/false</span>
-]
-
-<span class="muRecipe">def</span> fixup-delete env:address:programming-environment-data, next:address:sandbox-data<span class="muRecipe"> -&gt; </span>env:address:programming-environment-data [
-  <span class="Constant">local-scope</span>
-  <span class="Constant">load-ingredients</span>
   <span class="Comment"># update sandbox count</span>
   sandbox-count:number<span class="Special"> &lt;- </span>get *env, <span class="Constant">number-of-sandboxes:offset</span>
   sandbox-count<span class="Special"> &lt;- </span>subtract sandbox-count, <span class="Constant">1</span>
   *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">number-of-sandboxes:offset</span>, sandbox-count
+  <span class="Comment"># reset scroll if deleted sandbox was last</span>
   <span class="Delimiter">{</span>
-    <span class="muControl">break-if</span> next
-    <span class="Comment"># deleted sandbox was last</span>
+    <span class="muControl">break-if</span> next-sandbox
     render-from:number<span class="Special"> &lt;- </span>get *env, <span class="Constant">render-from:offset</span>
     reset-scroll?:boolean<span class="Special"> &lt;- </span>equal render-from, sandbox-count
     <span class="muControl">break-unless</span> reset-scroll?
-    <span class="Comment"># deleted sandbox was only sandbox rendered, so reset scroll</span>
     *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">render-from:offset</span>, <span class="Constant">-1</span>
   <span class="Delimiter">}</span>
 ]
 
 <span class="muScenario">scenario</span> deleting-sandbox-after-scroll [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># initialize environment</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
   <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
@@ -187,40 +196,40 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     press F4
     type <span class="Constant">[add 1, 1]</span>
     press F4
-    press down-arrow
+    press page-down
   ]
   event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
   ]
   <span class="Comment"># delete the second sandbox</span>
   assume-console [
-    left-click <span class="Constant">6</span>, <span class="Constant">29</span>
+    left-click <span class="Constant">6</span>, <span class="Constant">99</span>
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
 ]
 
 <span class="muScenario">scenario</span> deleting-top-sandbox-after-scroll [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># initialize environment</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
   <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
@@ -233,40 +242,40 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     press F4
     type <span class="Constant">[add 1, 1]</span>
     press F4
-    press down-arrow
+    press page-down
   ]
   event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
   ]
   <span class="Comment"># delete the second sandbox</span>
   assume-console [
-    left-click <span class="Constant">2</span>, <span class="Constant">29</span>
+    left-click <span class="Constant">2</span>, <span class="Constant">99</span>
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
 ]
 
 <span class="muScenario">scenario</span> deleting-final-sandbox-after-scroll [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># initialize environment</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
   <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
@@ -279,42 +288,42 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     press F4
     type <span class="Constant">[add 1, 1]</span>
     press F4
-    press down-arrow
-    press down-arrow
+    press page-down
+    press page-down
   ]
   event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
   <span class="Comment"># delete the second sandbox</span>
   assume-console [
-    left-click <span class="Constant">2</span>, <span class="Constant">29</span>
+    left-click <span class="Constant">2</span>, <span class="Constant">99</span>
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># implicitly scroll up to first sandbox</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊              .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
 ]
 
 <span class="muScenario">scenario</span> deleting-updates-sandbox-count [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">30/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># initialize environment</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
   <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
@@ -330,35 +339,35 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   ]
   event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊              .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊0            x.</span>
-   <span class="Constant"> .               ┊add 1, 1      .</span>
-   <span class="Constant"> .               ┊2             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊1            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
   ]
   <span class="Comment"># delete the second sandbox, then try to scroll down twice</span>
   assume-console [
-    left-click <span class="Constant">3</span>, <span class="Constant">29</span>
-    press down-arrow
-    press down-arrow
+    left-click <span class="Constant">3</span>, <span class="Constant">99</span>
+    press page-down
+    press page-down
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># shouldn't go past last sandbox</span>
   screen-should-contain [
-   <span class="Constant"> .                              .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0            x.</span>
-   <span class="Constant"> .               ┊add 2, 2      .</span>
-   <span class="Constant"> .               ┊4             .</span>
-   <span class="Constant"> .               ┊━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .               ┊              .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
 ]
 </pre>
diff --git a/html/edit/008-sandbox-edit.mu.html b/html/edit/008-sandbox-edit.mu.html
new file mode 100644
index 00000000..80712819
--- /dev/null
+++ b/html/edit/008-sandbox-edit.mu.html
@@ -0,0 +1,375 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
+<html>
+<head>
+<meta http-equiv="content-type" content="text/html; charset=UTF-8">
+<title>Mu - edit/008-sandbox-edit.mu</title>
+<meta name="Generator" content="Vim/7.4">
+<meta name="plugin-version" content="vim7.4_v2">
+<meta name="syntax" content="none">
+<meta name="settings" content="use_css,pre_wrap,no_foldcolumn,expand_tabs,prevent_copy=">
+<meta name="colorscheme" content="minimal">
+<style type="text/css">
+<!--
+pre { white-space: pre-wrap; font-family: monospace; color: #eeeeee; background-color: #080808; }
+body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color: #080808; }
+* { font-size: 12pt; font-size: 1em; }
+.muScenario { color: #00af00; }
+.Special { color: #c00000; }
+.Delimiter { color: #800080; }
+.muRecipe { color: #ff8700; }
+.Comment { color: #9090ff; }
+.Constant { color: #00a0a0; }
+.SalientComment { color: #00ffff; }
+.muControl { color: #c0a020; }
+-->
+</style>
+
+<script type='text/javascript'>
+<!--
+
+-->
+</script>
+</head>
+<body>
+<pre id='vimCodeElement'>
+<span class="SalientComment">## editing sandboxes after they've been created</span>
+
+<span class="muScenario">scenario</span> clicking-on-a-sandbox-moves-it-to-editor [
+  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+  <span class="Comment"># basic recipe</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
+<span class="Constant">recipe foo [</span>
+<span class="Constant">  reply 4</span>
+<span class="Constant">]</span>]
+  <span class="Comment"># run it</span>
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[foo]</span>
+  assume-console [
+    press F4
+  ]
+  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
+  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># click at left edge of 'edit' button</span>
+  assume-console [
+    left-click <span class="Constant">3</span>, <span class="Constant">55</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  <span class="Comment"># it pops back into editor</span>
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊foo                                              .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊                                                 .</span>
+   <span class="Constant"> .]                                                 ┊                                                 .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># cursor should be in the right place</span>
+  assume-console [
+    type <span class="Constant">[0]</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊0foo                                             .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊                                                 .</span>
+   <span class="Constant"> .]                                                 ┊                                                 .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+]
+
+<span class="muScenario">scenario</span> clicking-on-a-sandbox-moves-it-to-editor-2 [
+  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+  <span class="Comment"># basic recipe</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
+<span class="Constant">recipe foo [</span>
+<span class="Constant">  reply 4</span>
+<span class="Constant">]</span>]
+  <span class="Comment"># run it</span>
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[foo]</span>
+  assume-console [
+    press F4
+  ]
+  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
+  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># click at right edge of 'edit' button (just before 'copy')</span>
+  assume-console [
+    left-click <span class="Constant">3</span>, <span class="Constant">68</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  <span class="Comment"># it pops back into editor</span>
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊foo                                              .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊                                                 .</span>
+   <span class="Constant"> .]                                                 ┊                                                 .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># cursor should be in the right place</span>
+  assume-console [
+    type <span class="Constant">[0]</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊0foo                                             .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊                                                 .</span>
+   <span class="Constant"> .]                                                 ┊                                                 .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+]
+
+<span class="muRecipe">after</span> <span class="Constant">&lt;global-touch&gt;</span> [
+  <span class="Comment"># support 'edit' button</span>
+  <span class="Delimiter">{</span>
+    edit?:boolean<span class="Special"> &lt;- </span>should-attempt-edit? click-row, click-column, env
+    <span class="muControl">break-unless</span> edit?
+    edit?, env<span class="Special"> &lt;- </span>try-edit-sandbox click-row, env
+    <span class="muControl">break-unless</span> edit?
+    hide-screen screen
+    screen<span class="Special"> &lt;- </span>render-sandbox-side screen, env
+    screen<span class="Special"> &lt;- </span>update-cursor screen, recipes, current-sandbox, sandbox-in-focus?, env
+    show-screen screen
+    <span class="muControl">loop</span> <span class="Constant">+next-event:label</span>
+  <span class="Delimiter">}</span>
+]
+
+<span class="Comment"># some preconditions for attempting to edit a sandbox</span>
+<span class="muRecipe">def</span> should-attempt-edit? click-row:number, click-column:number, env:address:programming-environment-data<span class="muRecipe"> -&gt; </span>result:boolean [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  <span class="Comment"># are we below the sandbox editor?</span>
+  click-sandbox-area?:boolean<span class="Special"> &lt;- </span>click-on-sandbox-area? click-row, click-column, env
+  <span class="muControl">reply-unless</span> click-sandbox-area?, <span class="Constant">0/false</span>
+  <span class="Comment"># narrower, is the click in the columns spanning the 'edit' button?</span>
+  first-sandbox:address:editor-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">current-sandbox:offset</span>
+  assert first-sandbox, <span class="Constant">[!!]</span>
+  sandbox-left-margin:number<span class="Special"> &lt;- </span>get *first-sandbox, <span class="Constant">left:offset</span>
+  sandbox-right-margin:number<span class="Special"> &lt;- </span>get *first-sandbox, <span class="Constant">right:offset</span>
+  edit-button-left:number, edit-button-right:number, _<span class="Special"> &lt;- </span>sandbox-menu-columns sandbox-left-margin, sandbox-right-margin
+  edit-button-vertical-area?:boolean<span class="Special"> &lt;- </span>within-range? click-column, edit-button-left, edit-button-right
+  <span class="muControl">reply-unless</span> edit-button-vertical-area?, <span class="Constant">0/false</span>
+  <span class="Comment"># finally, is sandbox editor empty?</span>
+  current-sandbox:address:editor-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">current-sandbox:offset</span>
+  result<span class="Special"> &lt;- </span>empty-editor? current-sandbox
+]
+
+<span class="muRecipe">def</span> try-edit-sandbox click-row:number, env:address:programming-environment-data<span class="muRecipe"> -&gt; </span>clicked-on-edit-button?:boolean, env:address:programming-environment-data [
+  <span class="Constant">local-scope</span>
+  <span class="Constant">load-ingredients</span>
+  <span class="Comment"># identify the sandbox to edit, if the click was actually on the 'edit' button</span>
+  sandbox:address:sandbox-data<span class="Special"> &lt;- </span>find-sandbox env, click-row
+  <span class="muControl">return-unless</span> sandbox, <span class="Constant">0/false</span>
+  clicked-on-edit-button?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
+  <span class="Comment"># 'edit' button = 'copy' button + 'delete' button</span>
+  text:address:array:character<span class="Special"> &lt;- </span>get *sandbox, <span class="Constant">data:offset</span>
+  current-sandbox:address:editor-data<span class="Special"> &lt;- </span>get *env, <span class="Constant">current-sandbox:offset</span>
+  current-sandbox<span class="Special"> &lt;- </span>insert-text current-sandbox, text
+  env<span class="Special"> &lt;- </span>delete-sandbox env, sandbox
+  <span class="Comment"># reset scroll</span>
+  *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">render-from:offset</span>, <span class="Constant">-1</span>
+  <span class="Comment"># position cursor in sandbox editor</span>
+  *env<span class="Special"> &lt;- </span>put *env, <span class="Constant">sandbox-in-focus?:offset</span>, <span class="Constant">1/true</span>
+]
+
+<span class="muScenario">scenario</span> sandbox-with-print-can-be-edited [
+  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">20/height</span>
+  <span class="Comment"># left editor is empty</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
+  <span class="Comment"># right editor contains an instruction</span>
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[print-integer screen, 4]</span>
+  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
+  <span class="Comment"># run the sandbox</span>
+  assume-console [
+    press F4
+  ]
+  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊print-integer screen, 4                          .</span>
+   <span class="Constant"> .                                                  ┊screen:                                          .</span>
+   <span class="Constant"> .                                                  ┊  .4                             .               .</span>
+   <span class="Constant"> .                                                  ┊  .                              .               .</span>
+   <span class="Constant"> .                                                  ┊  .                              .               .</span>
+   <span class="Constant"> .                                                  ┊  .                              .               .</span>
+   <span class="Constant"> .                                                  ┊  .                              .               .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># edit the sandbox</span>
+  assume-console [
+    left-click <span class="Constant">3</span>, <span class="Constant">65</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊print-integer screen, 4                          .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+]
+
+<span class="muScenario">scenario</span> editing-sandbox-after-scrolling-resets-scroll [
+  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+  <span class="Comment"># initialize environment</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
+  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
+  render-all screen, <span class="Constant">3</span>:address:programming-environment-data
+  <span class="Comment"># create 2 sandboxes and scroll to second</span>
+  assume-console [
+    press ctrl-n
+    type <span class="Constant">[add 2, 2]</span>
+    press F4
+    type <span class="Constant">[add 1, 1]</span>
+    press F4
+    press page-down
+    press page-down
+  ]
+  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+  <span class="Comment"># edit the second sandbox</span>
+  assume-console [
+    left-click <span class="Constant">2</span>, <span class="Constant">55</span>
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  <span class="Comment"># second sandbox shows in editor; scroll resets to display first sandbox</span>
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+]
+
+<span class="muScenario">scenario</span> editing-sandbox-updates-sandbox-count [
+  trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
+  <span class="Comment"># initialize environment</span>
+  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
+  <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[]</span>
+  <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
+  render-all screen, <span class="Constant">3</span>:address:programming-environment-data
+  <span class="Comment"># create 2 sandboxes</span>
+  assume-console [
+    press ctrl-n
+    type <span class="Constant">[add 2, 2]</span>
+    press F4
+    type <span class="Constant">[add 1, 1]</span>
+    press F4
+  ]
+  event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+  ]
+  <span class="Comment"># edit the second sandbox, then resave</span>
+  assume-console [
+    left-click <span class="Constant">3</span>, <span class="Constant">60</span>
+    press F4
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  <span class="Comment"># no change in contents</span>
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 1, 1                                         .</span>
+   <span class="Constant"> .                                                  ┊2                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+  ]
+  <span class="Comment"># now try to scroll past end</span>
+  assume-console [
+    press page-down
+    press page-down
+    press page-down
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
+  ]
+  <span class="Comment"># screen should show just final sandbox with the right index (1)</span>
+  screen-should-contain [
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊1   edit          copy            delete         .</span>
+   <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
+   <span class="Constant"> .                                                  ┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+  ]
+]
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->
diff --git a/html/edit/008-sandbox-test.mu.html b/html/edit/009-sandbox-test.mu.html
index 69a4fd5c..5d7e782a 100644
--- a/html/edit/008-sandbox-test.mu.html
+++ b/html/edit/009-sandbox-test.mu.html
@@ -2,7 +2,7 @@
 <html>
 <head>
 <meta http-equiv="content-type" content="text/html; charset=UTF-8">
-<title>Mu - edit/008-sandbox-test.mu</title>
+<title>Mu - edit/009-sandbox-test.mu</title>
 <meta name="Generator" content="Vim/7.4">
 <meta name="plugin-version" content="vim7.4_v2">
 <meta name="syntax" content="none">
@@ -37,7 +37,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
 
 <span class="muScenario">scenario</span> sandbox-click-on-result-toggles-color-to-green [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">40/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># basic recipe</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
 <span class="Constant">recipe foo [</span>
@@ -51,32 +51,32 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
   event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  reply 4           ┊0                 x.</span>
-   <span class="Constant"> .]                   ┊foo                .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                  .</span>
-   <span class="Constant"> .                    ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                   .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
   <span class="Comment"># click on the '4' in the result</span>
   assume-console [
-    left-click <span class="Constant">5</span>, <span class="Constant">21</span>
+    left-click <span class="Constant">5</span>, <span class="Constant">51</span>
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># color toggles to green</span>
   screen-should-contain-in-color <span class="Constant">2/green</span>, [
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                     4                  .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                   4                                                .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
   ]
   <span class="Comment"># cursor should remain unmoved</span>
   run [
@@ -84,14 +84,16 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     print screen:address:screen, <span class="Constant">4</span>:character/cursor
   ]
   screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .␣                   ┊                   .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  reply 4           ┊0                 x.</span>
-   <span class="Constant"> .]                   ┊foo                .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                  .</span>
-   <span class="Constant"> .                    ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                   .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .␣                                                 ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  reply 4                                         ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
   <span class="Comment"># now change the result</span>
   <span class="Comment"># then rerun</span>
@@ -106,14 +108,14 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   ]
   <span class="Comment"># result turns red</span>
   screen-should-contain-in-color <span class="Constant">1/red</span>, [
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                     3                  .</span>
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                                        .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                   3                                                .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                                                                    .</span>
   ]
 ]
 
@@ -134,7 +136,12 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
 ]
 
 <span class="muRecipe">before</span> <span class="Constant">&lt;end-restore-sandbox&gt;</span> [
-  *curr<span class="Special"> &lt;- </span>put *curr, <span class="Constant">expected-response:offset</span>, contents
+  <span class="Delimiter">{</span>
+    filename<span class="Special"> &lt;- </span>append filename, <span class="Constant">[.out]</span>
+    contents<span class="Special"> &lt;- </span>restore filename
+    <span class="muControl">break-unless</span> contents
+    *curr<span class="Special"> &lt;- </span>put *curr, <span class="Constant">expected-response:offset</span>, contents
+  <span class="Delimiter">}</span>
 ]
 
 <span class="Comment"># clicks on sandbox responses save it as 'expected'</span>
diff --git a/html/edit/009-sandbox-trace.mu.html b/html/edit/010-sandbox-trace.mu.html
index c6d30308..282d2463 100644
--- a/html/edit/009-sandbox-trace.mu.html
+++ b/html/edit/010-sandbox-trace.mu.html
@@ -2,7 +2,7 @@
 <html>
 <head>
 <meta http-equiv="content-type" content="text/html; charset=UTF-8">
-<title>Mu - edit/009-sandbox-trace.mu</title>
+<title>Mu - edit/010-sandbox-trace.mu</title>
 <meta name="Generator" content="Vim/7.4">
 <meta name="plugin-version" content="vim7.4_v2">
 <meta name="syntax" content="none">
@@ -37,7 +37,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
 
 <span class="muScenario">scenario</span> sandbox-click-on-code-toggles-app-trace [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">40/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># basic recipe</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
 <span class="Constant">recipe foo [</span>
@@ -51,17 +51,17 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
   event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  stash [abc]       ┊0                 x.</span>
-   <span class="Constant"> .]                   ┊foo                .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                   .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  stash [abc]                                     ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
   <span class="Comment"># click on the code in the sandbox</span>
   assume-console [
-    left-click <span class="Constant">4</span>, <span class="Constant">21</span>
+    left-click <span class="Constant">4</span>, <span class="Constant">51</span>
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
@@ -70,28 +70,28 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   ]
   <span class="Comment"># trace now printed and cursor shouldn't have budged</span>
   screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .␣                   ┊                   .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  stash [abc]       ┊0                 x.</span>
-   <span class="Constant"> .]                   ┊foo                .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊abc                .</span>
-   <span class="Constant"> .                    ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                   .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .␣                                                 ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  stash [abc]                                     ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊abc                                              .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
   screen-should-contain-in-color <span class="Constant">245/grey</span>, [
-   <span class="Constant"> .                                        .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-   <span class="Constant"> .                    ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                  x.</span>
-   <span class="Constant"> .                    ┊                   .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊abc                .</span>
-   <span class="Constant"> .                    ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                   .</span>
+   <span class="Constant"> .                                                                                                    .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊abc                                              .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
   <span class="Comment"># click again on the same region</span>
   assume-console [
-    left-click <span class="Constant">4</span>, <span class="Constant">25</span>
+    left-click <span class="Constant">4</span>, <span class="Constant">55</span>
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
@@ -99,19 +99,19 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   ]
   <span class="Comment"># trace hidden again</span>
   screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .␣                   ┊                   .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  stash [abc]       ┊0                 x.</span>
-   <span class="Constant"> .]                   ┊foo                .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                   .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .␣                                                 ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  stash [abc]                                     ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .]                                                 ┊foo                                              .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
 ]
 
 <span class="muScenario">scenario</span> sandbox-shows-app-trace-and-result [
   trace-until <span class="Constant">100/app</span>  <span class="Comment"># trace too long</span>
-  assume-screen <span class="Constant">40/width</span>, <span class="Constant">10/height</span>
+  assume-screen <span class="Constant">100/width</span>, <span class="Constant">10/height</span>
   <span class="Comment"># basic recipe</span>
   <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ </span>
 <span class="Constant">recipe foo [</span>
@@ -126,33 +126,33 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
   <span class="Constant">3</span>:address:programming-environment-data<span class="Special"> &lt;- </span>new-programming-environment screen:address:screen, <span class="Constant">1</span>:address:array:character, <span class="Constant">2</span>:address:array:character
   event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  stash [abc]       ┊0                 x.</span>
-   <span class="Constant"> .  reply 4           ┊foo                .</span>
-   <span class="Constant"> .]                   ┊4                  .</span>
-<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                   .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  stash [abc]                                     ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .  reply 4                                         ┊foo                                              .</span>
+   <span class="Constant"> .]                                                 ┊4                                                .</span>
+<span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
   <span class="Comment"># click on the code in the sandbox</span>
   assume-console [
-    left-click <span class="Constant">4</span>, <span class="Constant">21</span>
+    left-click <span class="Constant">4</span>, <span class="Constant">51</span>
   ]
   run [
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   <span class="Comment"># trace now printed above result</span>
   screen-should-contain [
-   <span class="Constant"> .                     run (F4)           .</span>
-   <span class="Constant"> .                    ┊                   .</span>
-   <span class="Constant"> .recipe foo [        ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .  stash [abc]       ┊0                 x.</span>
-   <span class="Constant"> .  reply 4           ┊foo                .</span>
-   <span class="Constant"> .]                   ┊abc                .</span>
-   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                  .</span>
-   <span class="Constant"> .                    ┊━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                    ┊                   .</span>
+   <span class="Constant"> .                                                                                 run (F4)           .</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
+   <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .  stash [abc]                                     ┊0   edit          copy            delete         .</span>
+   <span class="Constant"> .  reply 4                                         ┊foo                                              .</span>
+   <span class="Constant"> .]                                                 ┊abc                                              .</span>
+   <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .</span>
+   <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
 ]
 
diff --git a/html/edit/010-errors.mu.html b/html/edit/011-errors.mu.html
index d1627ae7..9689ea9f 100644
--- a/html/edit/010-errors.mu.html
+++ b/html/edit/011-errors.mu.html
@@ -2,7 +2,7 @@
 <html>
 <head>
 <meta http-equiv="content-type" content="text/html; charset=UTF-8">
-<title>Mu - edit/010-errors.mu</title>
+<title>Mu - edit/011-errors.mu</title>
 <meta name="Generator" content="Vim/7.4">
 <meta name="plugin-version" content="vim7.4_v2">
 <meta name="syntax" content="none">
@@ -170,9 +170,9 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
    <span class="Constant"> .  get 123:number, foo:offset                      ┊                                                 .</span>
    <span class="Constant"> .]                                                 ┊                                                 .</span>
-   <span class="Constant"> .foo: unknown element foo in container number      ┊                                                 .</span>
+   <span class="Constant"> .foo: unknown element 'foo' in container 'number'  ┊                                                 .</span>
    <span class="Constant"> .foo: first ingredient of 'get' should be a contai↩┊                                                 .</span>
-   <span class="Constant"> .ner, but got 123:number                           ┊                                                 .</span>
+   <span class="Constant"> .ner, but got '123:number'                         ┊                                                 .</span>
    <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
@@ -182,9 +182,9 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                                    .</span>
    <span class="Constant"> .                                                                                                    .</span>
    <span class="Constant"> .                                                                                                    .</span>
-   <span class="Constant"> .foo: unknown element foo in container number                                                        .</span>
+   <span class="Constant"> .foo: unknown element 'foo' in container 'number'                                                    .</span>
    <span class="Constant"> .foo: first ingredient of 'get' should be a contai                                                   .</span>
-   <span class="Constant"> .ner, but got 123:number                                                                             .</span>
+   <span class="Constant"> .ner, but got '123:number'                                                                           .</span>
    <span class="Constant"> .                                                                                                    .</span>
   ]
 ]
@@ -253,7 +253,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     event-loop screen:address:screen, console:address:console, <span class="Constant">3</span>:address:programming-environment-data
   ]
   assume-console [
-    left-click <span class="Constant">3</span>, <span class="Constant">80</span>
+    left-click <span class="Constant">3</span>, <span class="Constant">58</span>
     press ctrl-k
     type <span class="Constant">[add 2, 2]</span>  <span class="Comment"># valid code</span>
     press F4  <span class="Comment"># update sandbox</span>
@@ -266,7 +266,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                 run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊0                                               x.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊add 2, 2                                         .</span>
    <span class="Constant"> .                                                  ┊4                                                .</span>
    <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
@@ -294,10 +294,10 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
    <span class="Constant"> .recipe foo x:_elem -&gt; z:_elem [                   ┊                                                 .</span>
    <span class="Constant"> .local-scope                                       ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .load-ingredients                                  ┊0                                               x.</span>
+   <span class="Constant"> .load-ingredients                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .y:address:number &lt;- copy 0                        ┊foo 2                                            .</span>
    <span class="Constant"> .z &lt;- add x, y                                     ┊foo_2: 'add' requires number ingredients, but go↩.</span>
-   <span class="Constant"> .]                                                 ┊t y                                              .</span>
+   <span class="Constant"> .]                                                 ┊t 'y'                                            .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
@@ -313,10 +313,10 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
    <span class="Constant"> .recipe foo x:_elem -&gt; z:_elem [                   ┊                                                 .</span>
    <span class="Constant"> .local-scope                                       ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .load-ingredients                                  ┊0                                               x.</span>
+   <span class="Constant"> .load-ingredients                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .y:address:number &lt;- copy 0                        ┊foo 2                                            .</span>
    <span class="Constant"> .z &lt;- add x, y                                     ┊foo_3: 'add' requires number ingredients, but go↩.</span>
-   <span class="Constant"> .]                                                 ┊t y                                              .</span>
+   <span class="Constant"> .]                                                 ┊t 'y'                                            .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
@@ -403,7 +403,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
    <span class="Constant"> .  x &lt;- copy 0                                     ┊                                                 .</span>
    <span class="Constant"> .]                                                 ┊                                                 .</span>
-   <span class="Constant"> .foo: missing type for x in 'x &lt;- copy 0'          ┊                                                 .</span>
+   <span class="Constant"> .foo: missing type for 'x' in 'x &lt;- copy 0'        ┊                                                 .</span>
   ]
 ]
 
@@ -462,7 +462,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .  get x:address:point, 1:offset                   ┊                                                 .</span>
    <span class="Constant"> .]                                                 ┊                                                 .</span>
    <span class="Constant"> .foo: first ingredient of 'get' should be a contai↩┊                                                 .</span>
-   <span class="Constant"> .ner, but got x:address:point                      ┊                                                 .</span>
+   <span class="Constant"> .ner, but got 'x:address:point'                    ┊                                                 .</span>
    <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
@@ -496,7 +496,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .  get *y:address:point, x:number                  ┊                                                 .</span>
    <span class="Constant"> .]                                                 ┊                                                 .</span>
    <span class="Constant"> .foo: second ingredient of 'get' should have type ↩┊                                                 .</span>
-   <span class="Constant"> .'offset', but got x:number                        ┊                                                 .</span>
+   <span class="Constant"> .'offset', but got 'x:number'                      ┊                                                 .</span>
    <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
@@ -524,7 +524,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .  local-scope                                     ┊                                                 .</span>
    <span class="Constant"> .  x:number &lt;- copy y:number                       ┊                                                 .</span>
    <span class="Constant"> .]                                                 ┊                                                 .</span>
-   <span class="Constant"> .foo: use before set: y                            ┊                                                 .</span>
+   <span class="Constant"> .foo: use before set: 'y'                          ┊                                                 .</span>
    <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
@@ -542,7 +542,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .  local-scope                                     ┊                                                 .</span>
    <span class="Constant"> .  x:number &lt;- copy y:number                       ┊                                                 .</span>
    <span class="Constant"> .]                                                 ┊                                                 .</span>
-   <span class="Constant"> .foo: use before set: y                            ┊                                                 .</span>
+   <span class="Constant"> .foo: use before set: 'y'                          ┊                                                 .</span>
    <span class="Constant"> .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
@@ -568,11 +568,11 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊0                                               x.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊get 1234:number, foo:offset                      .</span>
-   <span class="Constant"> .                                                  ┊unknown element foo in container number          .</span>
+   <span class="Constant"> .                                                  ┊unknown element 'foo' in container 'number'      .</span>
    <span class="Constant"> .                                                  ┊first ingredient of 'get' should be a container,↩.</span>
-   <span class="Constant"> .                                                  ┊ but got 1234:number                             .</span>
+   <span class="Constant"> .                                                  ┊ but got '1234:number'                           .</span>
    <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
@@ -592,16 +592,16 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .                                                                                                    .</span>
    <span class="Constant"> .                                                                                                    .</span>
    <span class="Constant"> .                                                                                                    .</span>
-   <span class="Constant"> .                                                   unknown element foo in container number          .</span>
+   <span class="Constant"> .                                                   unknown element 'foo' in container 'number'      .</span>
    <span class="Constant"> .                                                   first ingredient of 'get' should be a container, .</span>
-   <span class="Constant"> .                                                    but got 1234:number                             .</span>
+   <span class="Constant"> .                                                    but got '1234:number'                           .</span>
    <span class="Constant"> .                                                                                                    .</span>
   ]
   screen-should-contain-in-color <span class="Constant">245/grey</span>, [
    <span class="Constant"> .                                                                                                    .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊                                                x.</span>
+   <span class="Constant"> .                                                  ┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
    <span class="Constant"> .                                                  ┊                                                ↩.</span>
@@ -632,11 +632,11 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .                                                  ┊0                                               x.</span>
+   <span class="Constant"> .                                                  ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .                                                  ┊get 1234:number, foo:offset                      .</span>
-   <span class="Constant"> .                                                  ┊unknown element foo in container number          .</span>
+   <span class="Constant"> .                                                  ┊unknown element 'foo' in container 'number'      .</span>
    <span class="Constant"> .                                                  ┊first ingredient of 'get' should be a container,↩.</span>
-   <span class="Constant"> .                                                  ┊ but got 1234:number                             .</span>
+   <span class="Constant"> .                                                  ┊ but got '1234:number'                           .</span>
    <span class="Constant"> .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
    <span class="Constant"> .                                                  ┊                                                 .</span>
   ]
@@ -665,7 +665,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
    <span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
    <span class="Constant"> .recipe foo [                                      ┊                                                 .</span>
    <span class="Constant"> .  {                                               ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .    loop                                          ┊0                                               x.</span>
+   <span class="Constant"> .    loop                                          ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .  }                                               ┊foo                                              .</span>
    <span class="Constant"> .]                                                 ┊took too long!                                   .</span>
 <span class="Constant">    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
@@ -697,7 +697,7 @@ _, c:number<span class="Special"> &lt;- </span>divide-with-remainder a, b
    <span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
    <span class="Constant"> .recipe foo [                                      ┊                                                 .</span>
    <span class="Constant"> .local-scope                                       ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .a:number &lt;- next-ingredient                       ┊0                                               x.</span>
+   <span class="Constant"> .a:number &lt;- next-ingredient                       ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .b:number &lt;- next-ingredient                       ┊foo 4, 0                                         .</span>
    <span class="Constant"> .stash [dividing by], b                            ┊foo: divide by zero in '_, c:number &lt;- divide-wi↩.</span>
    <span class="Constant"> ._, c:number &lt;- divide-with-remainder a, b         ┊th-remainder a, b'                               .</span>
@@ -716,7 +716,7 @@ _, c:number<span class="Special"> &lt;- </span>divide-with-remainder a, b
    <span class="Constant"> .  errors found (0)                                                               run (F4)           .</span>
    <span class="Constant"> .recipe foo [                                      ┊                                                 .</span>
    <span class="Constant"> .local-scope                                       ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.</span>
-   <span class="Constant"> .a:number &lt;- next-ingredient                       ┊0                                               x.</span>
+   <span class="Constant"> .a:number &lt;- next-ingredient                       ┊0   edit          copy            delete         .</span>
    <span class="Constant"> .b:number &lt;- next-ingredient                       ┊foo 4, 0                                         .</span>
    <span class="Constant"> .stash [dividing by], b                            ┊dividing by 0                                    .</span>
    <span class="Constant"> ._, c:number &lt;- divide-with-remainder a, b         ┊foo: divide by zero in '_, c:number &lt;- divide-wi↩.</span>
diff --git a/html/edit/011-editor-undo.mu.html b/html/edit/012-editor-undo.mu.html
index 18d6843a..0518d0ad 100644
--- a/html/edit/011-editor-undo.mu.html
+++ b/html/edit/012-editor-undo.mu.html
@@ -2,7 +2,7 @@
 <html>
 <head>
 <meta http-equiv="content-type" content="text/html; charset=UTF-8">
-<title>Mu - edit/011-editor-undo.mu</title>
+<title>Mu - edit/012-editor-undo.mu</title>
 <meta name="Generator" content="Vim/7.4">
 <meta name="plugin-version" content="vim7.4_v2">
 <meta name="syntax" content="none">
@@ -1655,7 +1655,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color
     undo:address:list:address:operation<span class="Special"> &lt;- </span>get *editor, <span class="Constant">undo:offset</span>
     <span class="Delimiter">{</span>
       <span class="Comment"># if previous operation was an insert, coalesce this operation with it</span>
-      <span class="muControl">break-unless</span> *undo
+      <span class="muControl">break-unless</span> undo
       op:address:operation<span class="Special"> &lt;- </span>first undo
       deletion:delete-operation, is-delete?:boolean<span class="Special"> &lt;- </span>maybe-convert *op, <span class="Constant">delete:variant</span>
       <span class="muControl">break-unless</span> is-delete?