2981 - sandbox buttons implemented in edit/

4 files changed, 373 insertions, 119 deletions

diff --git a/edit/004-programming-environment.mu b/edit/004-programming-environment.mu
index a432d565..99584c56 100644
--- a/edit/004-programming-environment.mu
+++ b/edit/004-programming-environment.mu
@@ -86,6 +86,8 @@ def event-loop screen:address:screen, console:address:console, env:address:progr
       touch-type:number <- get t, type:offset
       is-left-click?:boolean <- equal touch-type, 65513/mouse-left
       loop-unless is-left-click?, +next-event:label
+      click-row:number <- get t, row:offset
+      click-column:number <- get t, column:offset
       # later exceptions for non-editor touches will go here
       <global-touch>
       # send to both editors
diff --git a/edit/006-sandbox-copy.mu b/edit/006-sandbox-copy.mu
new file mode 100644
index 00000000..867be5ff
--- /dev/null
+++ b/edit/006-sandbox-copy.mu
@@ -0,0 +1,284 @@
+## the 'copy' button makes it easy to duplicate a sandbox, and thence to
+## see code operate in multiple situations
+
+scenario copy-a-sandbox-to-editor [
+  trace-until 100/app  # trace too long
+  assume-screen 100/width, 10/height
+  # basic recipe
+  1:address:array:character <- new [ 
+recipe foo [
+  reply 4
+]]
+  # run it
+  2:address:array:character <- new [foo]
+  assume-console [
+    press F4
+  ]
+  3:address:programming-environment-data <- new-programming-environment screen:address:screen, 1:address:array:character, 2:address:array:character
+  event-loop screen:address:screen, console:address:console, 3:address:programming-environment-data
+  screen-should-contain [
+    .                                                                                 run (F4)           .
+    .                                                  ┊                                                 .
+    .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .  reply 4                                         ┊0   edit          copy            delete         .
+    .]                                                 ┊foo                                              .
+    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .
+    .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .                                                  ┊                                                 .
+  ]
+  # click at left edge of 'copy' button
+  assume-console [
+    left-click 3, 69
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, 3:address:programming-environment-data
+  ]
+  # it copies into editor
+  screen-should-contain [
+    .                                                                                 run (F4)           .
+    .                                                  ┊foo                                              .
+    .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .  reply 4                                         ┊0   edit          copy            delete         .
+    .]                                                 ┊foo                                              .
+    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .
+    .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .                                                  ┊                                                 .
+  ]
+  # cursor should be in the right place
+  assume-console [
+    type [0]
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, 3:address:programming-environment-data
+  ]
+  screen-should-contain [
+    .                                                                                 run (F4)           .
+    .                                                  ┊0foo                                             .
+    .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .  reply 4                                         ┊0   edit          copy            delete         .
+    .]                                                 ┊foo                                              .
+    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .
+    .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .                                                  ┊                                                 .
+  ]
+]
+
+scenario copy-a-sandbox-to-editor-2 [
+  trace-until 100/app  # trace too long
+  assume-screen 100/width, 10/height
+  # basic recipe
+  1:address:array:character <- new [ 
+recipe foo [
+  reply 4
+]]
+  # run it
+  2:address:array:character <- new [foo]
+  assume-console [
+    press F4
+  ]
+  3:address:programming-environment-data <- new-programming-environment screen:address:screen, 1:address:array:character, 2:address:array:character
+  event-loop screen:address:screen, console:address:console, 3:address:programming-environment-data
+  screen-should-contain [
+    .                                                                                 run (F4)           .
+    .                                                  ┊                                                 .
+    .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .  reply 4                                         ┊0   edit          copy            delete         .
+    .]                                                 ┊foo                                              .
+    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .
+    .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .                                                  ┊                                                 .
+  ]
+  # click at right edge of 'copy' button (just before 'delete')
+  assume-console [
+    left-click 3, 84
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, 3:address:programming-environment-data
+  ]
+  # it copies into editor
+  screen-should-contain [
+    .                                                                                 run (F4)           .
+    .                                                  ┊foo                                              .
+    .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .  reply 4                                         ┊0   edit          copy            delete         .
+    .]                                                 ┊foo                                              .
+    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .
+    .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .                                                  ┊                                                 .
+  ]
+  # cursor should be in the right place
+  assume-console [
+    type [0]
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, 3:address:programming-environment-data
+  ]
+  screen-should-contain [
+    .                                                                                 run (F4)           .
+    .                                                  ┊0foo                                             .
+    .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .  reply 4                                         ┊0   edit          copy            delete         .
+    .]                                                 ┊foo                                              .
+    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .
+    .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .                                                  ┊                                                 .
+  ]
+]
+
+after <global-touch> [
+  # support 'copy' button
+  {
+    copy?:boolean <- should-attempt-copy? click-row, click-column, env
+    break-unless copy?
+    copy?, env <- try-copy-sandbox click-row, env
+    break-unless copy?
+    hide-screen screen
+    screen <- render-sandbox-side screen, env
+    screen <- update-cursor screen, recipes, current-sandbox, sandbox-in-focus?, env
+    show-screen screen
+    loop +next-event:label
+  }
+]
+
+# some preconditions for attempting to copy a sandbox
+def should-attempt-copy? click-row:number, click-column:number, env:address:programming-environment-data -> result:boolean [
+  local-scope
+  load-ingredients
+  # are we below the sandbox editor?
+  click-sandbox-area?:boolean <- click-on-sandbox-area? click-row, click-column, env
+  reply-unless click-sandbox-area?, 0/false
+  # narrower, is the click in the columns spanning the 'copy' button?
+  first-sandbox:address:editor-data <- get *env, current-sandbox:offset
+  assert first-sandbox, [!!]
+  sandbox-left-margin:number <- get *first-sandbox, left:offset
+  sandbox-right-margin:number <- get *first-sandbox, right:offset
+  _, _, copy-button-left:number, copy-button-right:number, _ <- sandbox-menu-columns sandbox-left-margin, sandbox-right-margin
+  copy-button-vertical-area?:boolean <- within-range? click-column, copy-button-left, copy-button-right
+  reply-unless copy-button-vertical-area?, 0/false
+  # finally, is sandbox editor empty?
+  current-sandbox:address:editor-data <- get *env, current-sandbox:offset
+  result <- empty-editor? current-sandbox
+]
+
+def try-copy-sandbox click-row:number, env:address:programming-environment-data -> clicked-on-copy-button?:boolean, env:address:programming-environment-data [
+  local-scope
+  load-ingredients
+  # identify the sandbox to copy, if the click was actually on the 'copy' button
+  sandbox:address:sandbox-data <- find-sandbox env, click-row
+  return-unless sandbox, 0/false
+  clicked-on-copy-button? <- copy 1/true
+  text:address:array:character <- get *sandbox, data:offset
+  current-sandbox:address:editor-data <- get *env, current-sandbox:offset
+  current-sandbox <- insert-text current-sandbox, text
+  # reset scroll
+  *env <- put *env, render-from:offset, -1
+  # position cursor in sandbox editor
+  *env <- put *env, sandbox-in-focus?:offset, 1/true
+]
+
+def find-sandbox env:address:programming-environment-data, click-row:number -> result:address:sandbox-data [
+  local-scope
+  load-ingredients
+  curr-sandbox:address:sandbox-data <- get *env, sandbox:offset
+  {
+    start:number <- get *curr-sandbox, starting-row-on-screen:offset
+    found?:boolean <- equal click-row, start
+    return-if found?, curr-sandbox
+    curr-sandbox <- get *curr-sandbox, next-sandbox:offset
+    loop
+  }
+  return 0/not-found
+]
+
+def click-on-sandbox-area? click-row:number, click-column:number, env:address:programming-environment-data -> result:boolean [
+  local-scope
+  load-ingredients
+  current-sandbox:address:editor-data <- get *env, current-sandbox:offset
+  sandbox-left-margin:number <- get *current-sandbox, left:offset
+  on-sandbox-side?:boolean <- greater-or-equal click-column, sandbox-left-margin
+  return-unless on-sandbox-side?, 0/false
+  first-sandbox:address:sandbox-data <- get *env, sandbox:offset
+  return-unless first-sandbox, 0/false
+  first-sandbox-begins:number <- get *first-sandbox, starting-row-on-screen:offset
+  result <- greater-or-equal click-row, first-sandbox-begins
+]
+
+def empty-editor? editor:address:editor-data -> result:boolean [
+  local-scope
+  load-ingredients
+  head:address:duplex-list:character <- get *editor, data:offset
+  first:address:duplex-list:character <- next head
+  result <- not first
+]
+
+def within-range? x:number, low:number, high:number -> result:boolean [
+  local-scope
+  load-ingredients
+  not-too-far-left?:boolean <- greater-or-equal x, low
+  not-too-far-right?:boolean <- lesser-or-equal x, high
+  result <- and not-too-far-left? not-too-far-right?
+]
+
+scenario copy-fails-if-sandbox-editor-not-empty [
+  trace-until 100/app  # trace too long
+  assume-screen 100/width, 10/height
+  # basic recipe
+  1:address:array:character <- new [ 
+recipe foo [
+  reply 4
+]]
+  # run it
+  2:address:array:character <- new [foo]
+  assume-console [
+    press F4
+  ]
+  3:address:programming-environment-data <- new-programming-environment screen:address:screen, 1:address:array:character, 2:address:array:character
+  event-loop screen:address:screen, console:address:console, 3:address:programming-environment-data
+  screen-should-contain [
+    .                                                                                 run (F4)           .
+    .                                                  ┊                                                 .
+    .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .  reply 4                                         ┊0   edit          copy            delete         .
+    .]                                                 ┊foo                                              .
+    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .
+    .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .                                                  ┊                                                 .
+  ]
+  # type something into the sandbox editor, then click on the 'copy' button
+  assume-console [
+    left-click 2, 70  # put cursor in sandbox editor
+    type [0]  # type something
+    left-click 3, 70  # click 'copy' button
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, 3:address:programming-environment-data
+  ]
+  # copy doesn't happen
+  screen-should-contain [
+    .                                                                                 run (F4)           .
+    .                                                  ┊0                                                .
+    .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .  reply 4                                         ┊0   edit          copy            delete         .
+    .]                                                 ┊foo                                              .
+    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .
+    .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .                                                  ┊                                                 .
+  ]
+  # cursor should be in the right place
+  assume-console [
+    type [1]
+  ]
+  run [
+    event-loop screen:address:screen, console:address:console, 3:address:programming-environment-data
+  ]
+  screen-should-contain [
+    .                                                                                 run (F4)           .
+    .                                                  ┊01                                               .
+    .recipe foo [                                      ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .  reply 4                                         ┊0   edit          copy            delete         .
+    .]                                                 ┊foo                                              .
+    .┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┊4                                                .
+    .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
+    .                                                  ┊                                                 .
+  ]
+]
diff --git a/edit/007-sandbox-delete.mu b/edit/007-sandbox-delete.mu
index c915dc75..6e377e38 100644
--- a/edit/007-sandbox-delete.mu
+++ b/edit/007-sandbox-delete.mu
@@ -65,10 +65,12 @@ scenario deleting-sandboxes [
 ]
 
 after <global-touch> [
-  # on a sandbox delete icon? process delete
+  # support 'delete' button
   {
-    was-delete?:boolean <- try-delete-sandbox t, env
-    break-unless was-delete?
+    delete?:boolean <- should-attempt-delete? click-row, click-column, env
+    break-unless delete?
+    delete?, env <- try-delete-sandbox click-row, env
+    break-unless delete?
     hide-screen screen
     screen <- render-sandbox-side screen, env
     screen <- update-cursor screen, recipes, current-sandbox, sandbox-in-focus?, env
@@ -77,63 +79,70 @@ after <global-touch> [
   }
 ]
 
-def try-delete-sandbox t:touch-event, env:address:programming-environment-data -> was-delete?:boolean, env:address:programming-environment-data [
+# some preconditions for attempting to delete a sandbox
+def should-attempt-delete? click-row:number, click-column:number, env:address:programming-environment-data -> result:boolean [
   local-scope
   load-ingredients
-  click-column:number <- get t, column:offset
-  current-sandbox:address:editor-data <- get *env, current-sandbox:offset
-  right:number <- get *current-sandbox, right:offset
-  at-right?:boolean <- equal click-column, right
-  return-unless at-right?, 0/false
-  click-row:number <- get t, row:offset
+  # are we below the sandbox editor?
+  click-sandbox-area?:boolean <- click-on-sandbox-area? click-row, click-column, env
+  reply-unless click-sandbox-area?, 0/false
+  # narrower, is the click in the columns spanning the 'copy' button?
+  first-sandbox:address:editor-data <- get *env, current-sandbox:offset
+  assert first-sandbox, [!!]
+  sandbox-left-margin:number <- get *first-sandbox, left:offset
+  sandbox-right-margin:number <- get *first-sandbox, right:offset
+  _, _, _, _, delete-button-left:number <- sandbox-menu-columns sandbox-left-margin, sandbox-right-margin
+  result <- within-range? click-column, delete-button-left, sandbox-right-margin
+]
+
+def try-delete-sandbox click-row:number, env:address:programming-environment-data -> clicked-on-delete-button?:boolean, env:address:programming-environment-data [
+  local-scope
+  load-ingredients
+  # identify the sandbox to delete, if the click was actually on the 'delete' button
+  sandbox:address:sandbox-data <- find-sandbox env, click-row
+  return-unless sandbox, 0/false
+  clicked-on-delete-button? <- copy 1/true
+  env <- delete-sandbox env, sandbox
+]
+
+def delete-sandbox env:address:programming-environment-data, sandbox:address:sandbox-data -> env:address:programming-environment-data [
+  local-scope
+  load-ingredients
+  curr-sandbox:address:sandbox-data <- get *env, sandbox:offset
+  first-sandbox?:boolean <- equal curr-sandbox, sandbox
   {
-    first:address:sandbox-data <- get *env, sandbox:offset
-    reply-unless first, 0/false
-    target-row:number <- get *first, starting-row-on-screen:offset
-    delete-first?:boolean <- equal target-row, click-row
-    break-unless delete-first?
-    new-first:address:sandbox-data <- get *first, next-sandbox:offset
-    *env <- put *env, sandbox:offset, new-first
-    env <- fixup-delete env, new-first
-    return 1/true  # force rerender
+    # first sandbox? pop
+    break-unless first-sandbox?
+    next-sandbox:address:sandbox-data <- get *curr-sandbox, next-sandbox:offset
+    *env <- put *env, sandbox:offset, next-sandbox
   }
-  prev:address:sandbox-data <- get *env, sandbox:offset
-  assert prev, [failed to find any sandboxes!]
-  curr:address:sandbox-data <- get *prev, next-sandbox:offset
   {
-    break-unless curr
-    # more sandboxes to check
+    # not first sandbox?
+    break-if first-sandbox?
+    prev-sandbox:address:sandbox-data <- copy curr-sandbox
+    curr-sandbox <- get *curr-sandbox, next-sandbox:offset
     {
-      target-row:number <- get *curr, starting-row-on-screen:offset
-      delete-curr?:boolean <- equal target-row, click-row
-      break-unless delete-curr?
-      # delete this sandbox
-      next:address:sandbox-data <- get *curr, next-sandbox:offset
-      *prev <- put *prev, next-sandbox:offset, next
-      env <- fixup-delete env, next
-      return 1/true  # force rerender
+      assert curr-sandbox, [sandbox not found! something is wrong.]
+      found?:boolean <- equal curr-sandbox, sandbox
+      break-if found?
+      prev-sandbox <- copy curr-sandbox
+      curr-sandbox <- get *curr-sandbox, next-sandbox:offset
+      loop
     }
-    prev <- copy curr
-    curr <- get *curr, next-sandbox:offset
-    loop
+    # snip sandbox out of its list
+    next-sandbox:address:sandbox-data <- get *curr-sandbox, next-sandbox:offset
+    *prev-sandbox <- put *prev-sandbox, next-sandbox:offset, next-sandbox
   }
-  return 0/false
-]
-
-def fixup-delete env:address:programming-environment-data, next:address:sandbox-data -> env:address:programming-environment-data [
-  local-scope
-  load-ingredients
   # update sandbox count
   sandbox-count:number <- get *env, number-of-sandboxes:offset
   sandbox-count <- subtract sandbox-count, 1
   *env <- put *env, number-of-sandboxes:offset, sandbox-count
+  # reset scroll if deleted sandbox was last
   {
-    break-if next
-    # deleted sandbox was last
+    break-if next-sandbox
     render-from:number <- get *env, render-from:offset
     reset-scroll?:boolean <- equal render-from, sandbox-count
     break-unless reset-scroll?
-    # deleted sandbox was only sandbox rendered, so reset scroll
     *env <- put *env, render-from:offset, -1
   }
 ]
diff --git a/edit/008-sandbox-edit.mu b/edit/008-sandbox-edit.mu
index edea112d..df897a6e 100644
--- a/edit/008-sandbox-edit.mu
+++ b/edit/008-sandbox-edit.mu
@@ -25,7 +25,7 @@ recipe foo [
     .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
     .                                                  ┊                                                 .
   ]
-  # click at left edge of edit button
+  # click at left edge of 'edit' button
   assume-console [
     left-click 3, 55
   ]
@@ -85,7 +85,7 @@ recipe foo [
     .                                                  ┊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━.
     .                                                  ┊                                                 .
   ]
-  # click at right edge of edit button (just before 'copy')
+  # click at right edge of 'edit' button (just before 'copy')
   assume-console [
     left-click 3, 68
   ]
@@ -121,10 +121,12 @@ recipe foo [
 ]
 
 after <global-touch> [
-  # below sandbox editor? pop appropriate sandbox contents back into sandbox editor
+  # support 'edit' button
   {
-    was-edit?:boolean <- try-edit-sandbox t, env
-    break-unless was-edit?
+    edit?:boolean <- should-attempt-edit? click-row, click-column, env
+    break-unless edit?
+    edit?, env <- try-edit-sandbox click-row, env
+    break-unless edit?
     hide-screen screen
     screen <- render-sandbox-side screen, env
     screen <- update-cursor screen, recipes, current-sandbox, sandbox-in-focus?, env
@@ -133,83 +135,40 @@ after <global-touch> [
   }
 ]
 
-def try-edit-sandbox t:touch-event, env:address:programming-environment-data -> was-edit?:boolean, env:address:programming-environment-data [
+# some preconditions for attempting to edit a sandbox
+def should-attempt-edit? click-row:number, click-column:number, env:address:programming-environment-data -> result:boolean [
   local-scope
   load-ingredients
-  click-column:number <- get t, column:offset
-  current-sandbox:address:editor-data <- get *env, current-sandbox:offset
-  sandbox-left-margin:number <- get *current-sandbox, left:offset
-  on-sandbox-side?:boolean <- greater-or-equal click-column, sandbox-left-margin
-  return-unless on-sandbox-side?, 0/false
-  first-sandbox:address:sandbox-data <- get *env, sandbox:offset
-  return-unless first-sandbox, 0/false
-  first-sandbox-begins:number <- get *first-sandbox, starting-row-on-screen:offset
-  click-row:number <- get t, row:offset
-  below-sandbox-editor?:boolean <- greater-or-equal click-row, first-sandbox-begins
-  return-unless below-sandbox-editor?, 0/false
-  empty-sandbox-editor?:boolean <- empty-editor? current-sandbox
-  return-unless empty-sandbox-editor?, 0/false  # don't clobber existing contents
-  sandbox-right-margin:number <- get *current-sandbox, right:offset
+  # are we below the sandbox editor?
+  click-sandbox-area?:boolean <- click-on-sandbox-area? click-row, click-column, env
+  reply-unless click-sandbox-area?, 0/false
+  # narrower, is the click in the columns spanning the 'edit' button?
+  first-sandbox:address:editor-data <- get *env, current-sandbox:offset
+  assert first-sandbox, [!!]
+  sandbox-left-margin:number <- get *first-sandbox, left:offset
+  sandbox-right-margin:number <- get *first-sandbox, right:offset
   edit-button-left:number, edit-button-right:number, _ <- sandbox-menu-columns sandbox-left-margin, sandbox-right-margin
-  left-of-edit-button?:boolean <- lesser-than click-column, edit-button-left
-  return-if left-of-edit-button?, 0/false
-  right-of-edit-button?:boolean <- greater-than click-column, edit-button-right
-  return-if right-of-edit-button?, 0/false
-  # identify the sandbox to edit and remove it from the sandbox list
-  sandbox:address:sandbox-data <- extract-sandbox env, click-row
-  return-unless sandbox, 0/false
-  text:address:array:character <- get *sandbox, data:offset
-  current-sandbox <- insert-text current-sandbox, text
-  *env <- put *env, render-from:offset, -1
-  return 1/true
-]
-
-def empty-editor? editor:address:editor-data -> result:boolean [
-  local-scope
-  load-ingredients
-  head:address:duplex-list:character <- get *editor, data:offset
-  first:address:duplex-list:character <- next head
-  result <- not first
+  edit-button-vertical-area?:boolean <- within-range? click-column, edit-button-left, edit-button-right
+  reply-unless edit-button-vertical-area?, 0/false
+  # finally, is sandbox editor empty?
+  current-sandbox:address:editor-data <- get *env, current-sandbox:offset
+  result <- empty-editor? current-sandbox
 ]
 
-def extract-sandbox env:address:programming-environment-data, click-row:number -> result:address:sandbox-data, env:address:programming-environment-data [
+def try-edit-sandbox click-row:number, env:address:programming-environment-data -> clicked-on-edit-button?:boolean, env:address:programming-environment-data [
   local-scope
   load-ingredients
-  curr-sandbox:address:sandbox-data <- get *env, sandbox:offset
-  start:number <- get *curr-sandbox, starting-row-on-screen:offset
-  in-editor?:boolean <- lesser-than click-row, start
-  return-if in-editor?, 0
-  first-sandbox?:boolean <- equal click-row, start
-  {
-    # first sandbox? pop
-    break-unless first-sandbox?
-    next-sandbox:address:sandbox-data <- get *curr-sandbox, next-sandbox:offset
-    *env <- put *env, sandbox:offset, next-sandbox
-  }
-  {
-    # not first sandbox?
-    break-if first-sandbox?
-    prev-sandbox:address:sandbox-data <- copy curr-sandbox
-    curr-sandbox <- get *curr-sandbox, next-sandbox:offset
-    {
-      next-sandbox:address:sandbox-data <- get *curr-sandbox, next-sandbox:offset
-      break-unless next-sandbox
-      # if click-row < sandbox.next-sandbox.starting-row-on-screen, break
-      next-start:number <- get *next-sandbox, starting-row-on-screen:offset
-      found?:boolean <- lesser-than click-row, next-start
-      break-if found?
-      prev-sandbox <- copy curr-sandbox
-      curr-sandbox <- copy next-sandbox
-      loop
-    }
-    # snip sandbox out of its list
-    *prev-sandbox <- put *prev-sandbox, next-sandbox:offset, next-sandbox
-  }
-  result <- copy curr-sandbox
-  # update sandbox count
-  sandbox-count:number <- get *env, number-of-sandboxes:offset
-  sandbox-count <- subtract sandbox-count, 1
-  *env <- put *env, number-of-sandboxes:offset, sandbox-count
+  # identify the sandbox to edit, if the click was actually on the 'edit' button
+  sandbox:address:sandbox-data <- find-sandbox env, click-row
+  return-unless sandbox, 0/false
+  clicked-on-edit-button? <- copy 1/true
+  # 'edit' button = 'copy' button + 'delete' button
+  text:address:array:character <- get *sandbox, data:offset
+  current-sandbox:address:editor-data <- get *env, current-sandbox:offset
+  current-sandbox <- insert-text current-sandbox, text
+  env <- delete-sandbox env, sandbox
+  # reset scroll
+  *env <- put *env, render-from:offset, -1
   # position cursor in sandbox editor
   *env <- put *env, sandbox-in-focus?:offset, 1/true
 ]