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-rw-r--r--html/edit/003-shortcuts.mu.html816
1 files changed, 409 insertions, 407 deletions
diff --git a/html/edit/003-shortcuts.mu.html b/html/edit/003-shortcuts.mu.html
index 0f7a60da..243635b0 100644
--- a/html/edit/003-shortcuts.mu.html
+++ b/html/edit/003-shortcuts.mu.html
@@ -41,14 +41,14 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 <span class="muScenario">scenario</span> editor-inserts-two-spaces-on-tab [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># just one character in final line</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ab</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ab</span>
 <span class="Constant">cd]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   assume-console [
     press tab
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -74,18 +74,18 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-handles-backspace-key [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">1</span>
     press backspace
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -105,7 +105,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     delete-previous-character?:boolean<span class="Special"> &lt;- </span>equal *c, <span class="Constant">8/backspace</span>
     <span class="muControl">break-unless</span> delete-previous-character?
 <span class="Constant">    &lt;backspace-character-begin&gt;</span>
-    editor, screen, go-render?:boolean, backspaced-cell:address:duplex-list:character<span class="Special"> &lt;- </span>delete-before-cursor editor, screen
+    editor, screen, go-render?:boolean, backspaced-cell:address:shared:duplex-list:character<span class="Special"> &lt;- </span>delete-before-cursor editor, screen
 <span class="Constant">    &lt;backspace-character-end&gt;</span>
     <span class="muControl">reply</span>
   <span class="Delimiter">}</span>
@@ -114,19 +114,19 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 <span class="Comment"># return values:</span>
 <span class="Comment">#   go-render? - whether caller needs to update the screen</span>
 <span class="Comment">#   backspaced-cell - value deleted (or 0 if nothing was deleted) so we can save it for undo, etc.</span>
-<span class="muRecipe">recipe</span> delete-before-cursor editor:address:editor-data, screen:address:screen<span class="muRecipe"> -&gt; </span>editor:address:editor-data, screen:address:screen, go-render?:boolean, backspaced-cell:address:duplex-list:character [
+<span class="muRecipe">recipe</span> delete-before-cursor editor:address:shared:editor-data, screen:address:shared:screen<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data, screen:address:shared:screen, go-render?:boolean, backspaced-cell:address:shared:duplex-list:character [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
-  before-cursor:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
-  data:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
+  before-cursor:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
+  data:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
   <span class="Comment"># if at start of text (before-cursor at § sentinel), return</span>
-  prev:address:duplex-list:character<span class="Special"> &lt;- </span>prev *before-cursor
+  prev:address:shared:duplex-list:character<span class="Special"> &lt;- </span>prev *before-cursor
   go-render?, backspaced-cell<span class="Special"> &lt;- </span>copy <span class="Constant">0/no-more-render</span>, <span class="Constant">0/nothing-deleted</span>
   <span class="muControl">reply-unless</span> prev
   trace <span class="Constant">10</span>, <span class="Constant">[app]</span>, <span class="Constant">[delete-before-cursor]</span>
   original-row:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">cursor-row:offset</span>
   editor, scroll?:boolean<span class="Special"> &lt;- </span>move-cursor-coordinates-left editor
-  backspaced-cell:address:duplex-list:character<span class="Special"> &lt;- </span>copy *before-cursor
+  backspaced-cell:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy *before-cursor
   data<span class="Special"> &lt;- </span>remove *before-cursor, data  <span class="Comment"># will also neatly trim next/prev pointers in backspaced-cell/*before-cursor</span>
   *before-cursor<span class="Special"> &lt;- </span>copy prev
   go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
@@ -140,7 +140,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
   <span class="muControl">reply-unless</span> same-row?
   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>
-  curr:address:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
+  curr:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
   screen<span class="Special"> &lt;- </span>move-cursor screen, cursor-row, cursor-column
   curr-column:number<span class="Special"> &lt;- </span>copy cursor-column
   <span class="Delimiter">{</span>
@@ -159,14 +159,15 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     <span class="muControl">loop</span>
   <span class="Delimiter">}</span>
   <span class="Comment"># we're guaranteed not to be at the right margin</span>
-  screen<span class="Special"> &lt;- </span>print screen, <span class="Constant">32/space</span>
+  space:character<span class="Special"> &lt;- </span>copy <span class="Constant">32/space</span>
+  screen<span class="Special"> &lt;- </span>print screen, space
   go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
 ]
 
-<span class="muRecipe">recipe</span> move-cursor-coordinates-left editor:address:editor-data<span class="muRecipe"> -&gt; </span>editor:address:editor-data, go-render?:boolean [
+<span class="muRecipe">recipe</span> move-cursor-coordinates-left editor:address:shared:editor-data<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data, go-render?:boolean [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
-  before-cursor:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">before-cursor:offset</span>
+  before-cursor:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">before-cursor:offset</span>
   cursor-row:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-row:offset</span>
   cursor-column:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-column:offset</span>
   left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
@@ -198,7 +199,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     <span class="muControl">break-unless</span> previous-character-is-newline?
     <span class="Comment"># compute length of previous line</span>
     trace <span class="Constant">10</span>, <span class="Constant">[app]</span>, <span class="Constant">[switching to previous line]</span>
-    d:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
+    d:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
     end-of-line:number<span class="Special"> &lt;- </span>previous-line-length before-cursor, d
     *cursor-column<span class="Special"> &lt;- </span>add left, end-of-line
     <span class="muControl">reply</span>
@@ -211,7 +212,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="Comment"># takes a pointer 'curr' into the doubly-linked list and its sentinel, counts</span>
 <span class="Comment"># the length of the previous line before the 'curr' pointer.</span>
-<span class="muRecipe">recipe</span> previous-line-length curr:address:duplex-list:character, start:address:duplex-list:character<span class="muRecipe"> -&gt; </span>result:number [
+<span class="muRecipe">recipe</span> previous-line-length curr:address:shared:duplex-list:character, start:address:shared:duplex-list:character<span class="muRecipe"> -&gt; </span>result:number [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   result:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
@@ -234,17 +235,17 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 <span class="muScenario">scenario</span> editor-clears-last-line-on-backspace [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># just one character in final line</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ab</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ab</span>
 <span class="Constant">cd]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   assume-console [
     left-click <span class="Constant">2</span>, <span class="Constant">0</span>  <span class="Comment"># cursor at only character in final line</span>
     press backspace
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -261,10 +262,10 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 <span class="muScenario">scenario</span> editor-joins-and-wraps-lines-on-backspace [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># initialize editor with two long-ish but non-wrapping lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc def</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc def</span>
 <span class="Constant">ghi jkl]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># position the cursor at the start of the second and hit backspace</span>
   assume-console [
@@ -272,7 +273,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     press backspace
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># resulting single line should wrap correctly</span>
   screen-should-contain [
@@ -287,9 +288,9 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 <span class="muScenario">scenario</span> editor-wraps-long-lines-on-backspace [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># initialize editor in part of the screen with a long line</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc def ghij]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">8/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc def ghij]</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">8/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
   <span class="Comment"># confirm that it wraps</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -304,7 +305,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     press backspace
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># resulting single line should wrap correctly and not overflow its bounds</span>
   screen-should-contain [
@@ -320,15 +321,15 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-handles-delete-key [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     press delete
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -342,7 +343,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     press delete
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -358,18 +359,18 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     delete-next-character?:boolean<span class="Special"> &lt;- </span>equal *k, <span class="Constant">65522/delete</span>
     <span class="muControl">break-unless</span> delete-next-character?
 <span class="Constant">    &lt;delete-character-begin&gt;</span>
-    editor, screen, go-render?:boolean, deleted-cell:address:duplex-list:character<span class="Special"> &lt;- </span>delete-at-cursor editor, screen
+    editor, screen, go-render?:boolean, deleted-cell:address:shared:duplex-list:character<span class="Special"> &lt;- </span>delete-at-cursor editor, screen
 <span class="Constant">    &lt;delete-character-end&gt;</span>
     <span class="muControl">reply</span>
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">recipe</span> delete-at-cursor editor:address:editor-data, screen:address:screen<span class="muRecipe"> -&gt; </span>editor:address:editor-data, screen:address:screen, go-render?:boolean, deleted-cell:address:duplex-list:character [
+<span class="muRecipe">recipe</span> delete-at-cursor editor:address:shared:editor-data, screen:address:shared:screen<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data, screen:address:shared:screen, go-render?:boolean, deleted-cell:address:shared:duplex-list:character [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
-  before-cursor:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
-  data:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
-  deleted-cell:address:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
+  before-cursor:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
+  data:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
+  deleted-cell:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
   go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
   <span class="muControl">reply-unless</span> deleted-cell
   currc:character<span class="Special"> &lt;- </span>get *deleted-cell, <span class="Constant">value:offset</span>
@@ -378,7 +379,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
   go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
   <span class="muControl">reply-if</span> deleted-newline?
   <span class="Comment"># wasn't a newline? render rest of line</span>
-  curr:address:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor  <span class="Comment"># refresh after remove above</span>
+  curr:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor  <span class="Comment"># refresh after remove above</span>
   cursor-row:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-row:offset</span>
   cursor-column:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-column:offset</span>
   screen<span class="Special"> &lt;- </span>move-cursor screen, *cursor-row, *cursor-column
@@ -400,7 +401,8 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     <span class="muControl">loop</span>
   <span class="Delimiter">}</span>
   <span class="Comment"># we're guaranteed not to be at the right margin</span>
-  screen<span class="Special"> &lt;- </span>print screen, <span class="Constant">32/space</span>
+  space:character<span class="Special"> &lt;- </span>copy <span class="Constant">32/space</span>
+  screen<span class="Special"> &lt;- </span>print screen, space
   go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
 ]
 
@@ -408,16 +410,16 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-moves-cursor-right-with-key [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     press right-arrow
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -433,7 +435,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     move-to-next-character?:boolean<span class="Special"> &lt;- </span>equal *k, <span class="Constant">65514/right-arrow</span>
     <span class="muControl">break-unless</span> move-to-next-character?
     <span class="Comment"># if not at end of text</span>
-    next-cursor:address:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
+    next-cursor:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
     <span class="muControl">break-unless</span> next-cursor
     <span class="Comment"># scan to next character</span>
 <span class="Constant">    &lt;move-cursor-begin&gt;</span>
@@ -446,10 +448,10 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">recipe</span> move-cursor-coordinates-right editor:address:editor-data, screen-height:number<span class="muRecipe"> -&gt; </span>editor:address:editor-data, go-render?:boolean [
+<span class="muRecipe">recipe</span> move-cursor-coordinates-right editor:address:shared:editor-data, screen-height:number<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data, go-render?:boolean [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
-  before-cursor:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor <span class="Constant">before-cursor:offset</span>
+  before-cursor:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor <span class="Constant">before-cursor:offset</span>
   cursor-row:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-row:offset</span>
   cursor-column:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-column:offset</span>
   left:number<span class="Special"> &lt;- </span>get *editor, <span class="Constant">left:offset</span>
@@ -476,7 +478,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     at-wrap?:boolean<span class="Special"> &lt;- </span>equal *cursor-column, wrap-column
     <span class="muControl">break-unless</span> at-wrap?
     <span class="Comment"># and if next character isn't newline</span>
-    next:address:duplex-list:character<span class="Special"> &lt;- </span>next before-cursor
+    next:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next before-cursor
     <span class="muControl">break-unless</span> next
     next-character:character<span class="Special"> &lt;- </span>get *next, <span class="Constant">value:offset</span>
     newline?:boolean<span class="Special"> &lt;- </span>equal next-character, <span class="Constant">10/newline</span>
@@ -497,10 +499,10 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-moves-cursor-to-next-line-with-right-arrow [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># type right-arrow a few times to get to start of second line</span>
   assume-console [
@@ -510,7 +512,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     press right-arrow  <span class="Comment"># next line</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   check-trace-count-for-label <span class="Constant">0</span>, <span class="Constant">[print-character]</span>
   <span class="Comment"># type something and ensure it goes where it should</span>
@@ -518,7 +520,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -532,10 +534,10 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-moves-cursor-to-next-line-with-right-arrow-2 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">1/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">1/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
   assume-console [
     press right-arrow
     press right-arrow
@@ -544,7 +546,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -557,18 +559,18 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-moves-cursor-to-next-wrapped-line-with-right-arrow [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef]</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">3</span>
     press right-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -587,9 +589,9 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 <span class="muScenario">scenario</span> editor-moves-cursor-to-next-wrapped-line-with-right-arrow-2 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># line just barely wrapping</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcde]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcde]</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># position cursor at last character before wrap and hit right-arrow</span>
   assume-console [
@@ -597,9 +599,9 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     press right-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">2</span>
@@ -610,9 +612,9 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     press right-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">2</span>
@@ -623,18 +625,18 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-moves-cursor-to-next-wrapped-line-with-right-arrow-3 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">1/left</span>, <span class="Constant">6/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef]</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">1/left</span>, <span class="Constant">6/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">4</span>
     press right-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -652,10 +654,10 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-moves-cursor-to-next-line-with-right-arrow-at-end-of-line [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># move to end of line, press right-arrow, type a character</span>
   assume-console [
@@ -664,7 +666,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># new character should be in next line</span>
   screen-should-contain [
@@ -683,9 +685,9 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-moves-cursor-left-with-key [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc]</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">2</span>
@@ -693,7 +695,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -710,7 +712,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     <span class="muControl">break-unless</span> move-to-previous-character?
     trace <span class="Constant">10</span>, <span class="Constant">[app]</span>, <span class="Constant">[left arrow]</span>
     <span class="Comment"># if not at start of text (before-cursor at § sentinel)</span>
-    prev:address:duplex-list:character<span class="Special"> &lt;- </span>prev *before-cursor
+    prev:address:shared:duplex-list:character<span class="Special"> &lt;- </span>prev *before-cursor
     go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
     <span class="muControl">reply-unless</span> prev
 <span class="Constant">    &lt;move-cursor-begin&gt;</span>
@@ -725,10 +727,10 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 <span class="muScenario">scenario</span> editor-moves-cursor-to-previous-line-with-left-arrow-at-start-of-line [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># initialize editor with two lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># position cursor at start of second line (so there's no previous newline)</span>
   assume-console [
@@ -736,9 +738,9 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     press left-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>
@@ -750,11 +752,11 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 <span class="muScenario">scenario</span> editor-moves-cursor-to-previous-line-with-left-arrow-at-start-of-line-2 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># initialize editor with three lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">def</span>
 <span class="Constant">g]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># position cursor further down (so there's a newline before the character at</span>
   <span class="Comment"># the cursor)</span>
@@ -764,7 +766,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -778,11 +780,11 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 
 <span class="muScenario">scenario</span> editor-moves-cursor-to-previous-line-with-left-arrow-at-start-of-line-3 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">def</span>
 <span class="Constant">g]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># position cursor at start of text, press left-arrow, then type a character</span>
   assume-console [
@@ -791,7 +793,7 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># left-arrow should have had no effect</span>
   screen-should-contain [
@@ -807,11 +809,11 @@ body { font-family: monospace; color: #eeeeee; background-color: #080808; }
 <span class="muScenario">scenario</span> editor-moves-cursor-to-previous-line-with-left-arrow-at-start-of-line-4 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># initialize editor with text containing an empty line</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 
 d]
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># position cursor right after empty line</span>
   assume-console [
@@ -820,7 +822,7 @@ d]
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -835,9 +837,9 @@ d]
 <span class="muScenario">scenario</span> editor-moves-across-screen-lines-across-wrap-with-left-arrow [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># initialize editor with text containing an empty line</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef]</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -852,9 +854,9 @@ d]
     press left-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># previous row</span>
@@ -869,19 +871,19 @@ d]
 
 <span class="muScenario">scenario</span> editor-moves-to-previous-line-with-up-arrow [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">def]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     left-click <span class="Constant">2</span>, <span class="Constant">1</span>
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>
@@ -892,7 +894,7 @@ d]
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -915,12 +917,12 @@ d]
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">recipe</span> move-to-previous-line editor:address:editor-data<span class="muRecipe"> -&gt; </span>editor:address:editor-data, go-render?:boolean [
+<span class="muRecipe">recipe</span> move-to-previous-line editor:address:shared:editor-data<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data, go-render?:boolean [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   cursor-row:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-row:offset</span>
   cursor-column:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-column:offset</span>
-  before-cursor:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
+  before-cursor:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
   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>
   already-at-top?:boolean<span class="Special"> &lt;- </span>lesser-or-equal *cursor-row, <span class="Constant">1/top</span>
@@ -930,13 +932,13 @@ d]
     <span class="Comment"># if not at newline, move to start of line (previous newline)</span>
     <span class="Comment"># then scan back another line</span>
     <span class="Comment"># if either step fails, give up without modifying cursor or coordinates</span>
-    curr:address:duplex-list:character<span class="Special"> &lt;- </span>copy *before-cursor
+    curr:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy *before-cursor
     <span class="Delimiter">{</span>
-      old:address:duplex-list:character<span class="Special"> &lt;- </span>copy curr
+      old:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy curr
       c2:character<span class="Special"> &lt;- </span>get *curr, <span class="Constant">value:offset</span>
       at-newline?:boolean<span class="Special"> &lt;- </span>equal c2, <span class="Constant">10/newline</span>
       <span class="muControl">break-if</span> at-newline?
-      curr:address:duplex-list:character<span class="Special"> &lt;- </span>before-previous-line curr, editor
+      curr:address:shared:duplex-list:character<span class="Special"> &lt;- </span>before-previous-line curr, editor
       no-motion?:boolean<span class="Special"> &lt;- </span>equal curr, old
       go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
       <span class="muControl">reply-if</span> no-motion?
@@ -956,7 +958,7 @@ d]
     <span class="Delimiter">{</span>
       done?:boolean<span class="Special"> &lt;- </span>greater-or-equal *cursor-column, target-column
       <span class="muControl">break-if</span> done?
-      curr:address:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
+      curr:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
       <span class="muControl">break-unless</span> curr
       currc:character<span class="Special"> &lt;- </span>get *curr, <span class="Constant">value:offset</span>
       at-newline?:boolean<span class="Special"> &lt;- </span>equal currc, <span class="Constant">10/newline</span>
@@ -980,19 +982,19 @@ d]
 
 <span class="muScenario">scenario</span> editor-adjusts-column-at-previous-line [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ab</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[ab</span>
 <span class="Constant">def]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     left-click <span class="Constant">2</span>, <span class="Constant">3</span>
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>
@@ -1003,7 +1005,7 @@ d]
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -1016,19 +1018,19 @@ d]
 
 <span class="muScenario">scenario</span> editor-adjusts-column-at-empty-line [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new [
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new [
 def]
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     left-click <span class="Constant">2</span>, <span class="Constant">3</span>
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>
@@ -1039,7 +1041,7 @@ def]
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -1053,11 +1055,11 @@ def]
 <span class="muScenario">scenario</span> editor-moves-to-previous-line-from-left-margin [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># start out with three lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">def</span>
 <span class="Constant">ghi]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># click on the third line and hit up-arrow, so you end up just after a newline</span>
   assume-console [
@@ -1065,9 +1067,9 @@ def]
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">2</span>
@@ -1078,7 +1080,7 @@ def]
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -1093,19 +1095,19 @@ def]
 
 <span class="muScenario">scenario</span> editor-moves-to-next-line-with-down-arrow [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">def]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># cursor starts out at (1, 0)</span>
   assume-console [
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># ..and ends at (2, 0)</span>
   memory-should-contain [
@@ -1117,7 +1119,7 @@ def]
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -1140,12 +1142,12 @@ def]
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">recipe</span> move-to-next-line editor:address:editor-data, screen-height:number<span class="muRecipe"> -&gt; </span>editor:address:editor-data, go-render?:boolean [
+<span class="muRecipe">recipe</span> move-to-next-line editor:address:shared:editor-data, screen-height:number<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data, go-render?:boolean [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   cursor-row:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-row:offset</span>
   cursor-column:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-column:offset</span>
-  before-cursor:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
+  before-cursor:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
   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>
   last-line:number<span class="Special"> &lt;- </span>subtract screen-height, <span class="Constant">1</span>
@@ -1155,7 +1157,7 @@ def]
     <span class="muControl">break-if</span> already-at-bottom?
     <span class="Comment"># scan to start of next line, then to right column or until end of line</span>
     max:number<span class="Special"> &lt;- </span>subtract right, left
-    next-line:address:duplex-list:character<span class="Special"> &lt;- </span>before-start-of-next-line *before-cursor, max
+    next-line:address:shared:duplex-list:character<span class="Special"> &lt;- </span>before-start-of-next-line *before-cursor, max
     <span class="Delimiter">{</span>
       <span class="Comment"># already at end of buffer? try to scroll up (so we can see more</span>
       <span class="Comment"># warnings or sandboxes below)</span>
@@ -1173,7 +1175,7 @@ def]
     <span class="Delimiter">{</span>
       done?:boolean<span class="Special"> &lt;- </span>greater-or-equal *cursor-column, target-column
       <span class="muControl">break-if</span> done?
-      curr:address:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
+      curr:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
       <span class="muControl">break-unless</span> curr
       currc:character<span class="Special"> &lt;- </span>get *curr, <span class="Constant">value:offset</span>
       at-newline?:boolean<span class="Special"> &lt;- </span>equal currc, <span class="Constant">10/newline</span>
@@ -1193,19 +1195,19 @@ def]
 
 <span class="muScenario">scenario</span> editor-adjusts-column-at-next-line [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">de]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">3</span>
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">2</span>
@@ -1216,7 +1218,7 @@ def]
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -1231,10 +1233,10 @@ def]
 
 <span class="muScenario">scenario</span> editor-moves-to-start-of-line-with-ctrl-a [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># start on second line, press ctrl-a</span>
   assume-console [
@@ -1242,9 +1244,9 @@ def]
     press ctrl-a
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># cursor moves to start of line</span>
   memory-should-contain [
@@ -1280,7 +1282,7 @@ def]
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">recipe</span> move-to-start-of-line editor:address:editor-data<span class="muRecipe"> -&gt; </span>editor:address:editor-data [
+<span class="muRecipe">recipe</span> move-to-start-of-line editor:address:shared:editor-data<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   <span class="Comment"># update cursor column</span>
@@ -1288,8 +1290,8 @@ def]
   cursor-column:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-column:offset</span>
   *cursor-column<span class="Special"> &lt;- </span>copy left
   <span class="Comment"># update before-cursor</span>
-  before-cursor:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
-  init:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
+  before-cursor:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
+  init:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
   <span class="Comment"># while not at start of line, move </span>
   <span class="Delimiter">{</span>
     at-start-of-text?:boolean<span class="Special"> &lt;- </span>equal *before-cursor, init
@@ -1305,10 +1307,10 @@ def]
 
 <span class="muScenario">scenario</span> editor-moves-to-start-of-line-with-ctrl-a-2 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># start on first line (no newline before), press ctrl-a</span>
   assume-console [
@@ -1316,9 +1318,9 @@ def]
     press ctrl-a
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># cursor moves to start of line</span>
   memory-should-contain [
@@ -1330,9 +1332,9 @@ def]
 
 <span class="muScenario">scenario</span> editor-moves-to-start-of-line-with-home [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># start on second line, press 'home'</span>
   assume-console [
@@ -1340,9 +1342,9 @@ def]
     press home
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># cursor moves to start of line</span>
   memory-should-contain [
@@ -1354,10 +1356,10 @@ def]
 
 <span class="muScenario">scenario</span> editor-moves-to-start-of-line-with-home-2 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># start on first line (no newline before), press 'home'</span>
   assume-console [
@@ -1365,9 +1367,9 @@ def]
     press home
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># cursor moves to start of line</span>
   memory-should-contain [
@@ -1381,10 +1383,10 @@ def]
 
 <span class="muScenario">scenario</span> editor-moves-to-end-of-line-with-ctrl-e [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># start on first line, press ctrl-e</span>
   assume-console [
@@ -1392,9 +1394,9 @@ def]
     press ctrl-e
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># cursor moves to end of line</span>
   memory-should-contain [
@@ -1407,9 +1409,9 @@ def]
     type <span class="Constant">[z]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   memory-should-contain [
     <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">1</span>
@@ -1451,14 +1453,14 @@ def]
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">recipe</span> move-to-end-of-line editor:address:editor-data<span class="muRecipe"> -&gt; </span>editor:address:editor-data [
+<span class="muRecipe">recipe</span> move-to-end-of-line editor:address:shared:editor-data<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
-  before-cursor:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
+  before-cursor:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
   cursor-column:address:number<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">cursor-column:offset</span>
   <span class="Comment"># while not at start of line, move </span>
   <span class="Delimiter">{</span>
-    next:address:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
+    next:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
     <span class="muControl">break-unless</span> next  <span class="Comment"># end of text</span>
     nextc:character<span class="Special"> &lt;- </span>get *next, <span class="Constant">value:offset</span>
     at-end-of-line?:boolean<span class="Special"> &lt;- </span>equal nextc, <span class="Constant">10/newline</span>
@@ -1471,10 +1473,10 @@ def]
 
 <span class="muScenario">scenario</span> editor-moves-to-end-of-line-with-ctrl-e-2 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># start on second line (no newline after), press ctrl-e</span>
   assume-console [
@@ -1482,9 +1484,9 @@ def]
     press ctrl-e
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">5</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># cursor moves to end of line</span>
   memory-should-contain [
@@ -1496,10 +1498,10 @@ def]
 
 <span class="muScenario">scenario</span> editor-moves-to-end-of-line-with-end [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># start on first line, press 'end'</span>
   assume-console [
@@ -1507,9 +1509,9 @@ def]
     press end
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># cursor moves to end of line</span>
   memory-should-contain [
@@ -1521,10 +1523,10 @@ def]
 
 <span class="muScenario">scenario</span> editor-moves-to-end-of-line-with-end-2 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># start on second line (no newline after), press 'end'</span>
   assume-console [
@@ -1532,9 +1534,9 @@ def]
     press end
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># cursor moves to end of line</span>
   memory-should-contain [
@@ -1548,16 +1550,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-start-of-line-with-ctrl-u [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start on second line, press ctrl-u</span>
   assume-console [
     left-click <span class="Constant">2</span>, <span class="Constant">2</span>
     press ctrl-u
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes to start of line</span>
   screen-should-contain [
@@ -1574,21 +1576,21 @@ def]
     delete-to-start-of-line?:boolean<span class="Special"> &lt;- </span>equal *c, <span class="Constant">21/ctrl-u</span>
     <span class="muControl">break-unless</span> delete-to-start-of-line?
 <span class="Constant">    &lt;delete-to-start-of-line-begin&gt;</span>
-    deleted-cells:address:duplex-list:character<span class="Special"> &lt;- </span>delete-to-start-of-line editor
+    deleted-cells:address:shared:duplex-list:character<span class="Special"> &lt;- </span>delete-to-start-of-line editor
 <span class="Constant">    &lt;delete-to-start-of-line-end&gt;</span>
     go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
     <span class="muControl">reply</span>
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">recipe</span> delete-to-start-of-line editor:address:editor-data<span class="muRecipe"> -&gt; </span>result:address:duplex-list:character, editor:address:editor-data [
+<span class="muRecipe">recipe</span> delete-to-start-of-line editor:address:shared:editor-data<span class="muRecipe"> -&gt; </span>result:address:shared:duplex-list:character, editor:address:shared:editor-data [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   <span class="Comment"># compute range to delete</span>
-  init:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
-  before-cursor:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
-  start:address:duplex-list:character<span class="Special"> &lt;- </span>copy *before-cursor
-  end:address:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
+  init:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
+  before-cursor:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
+  start:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy *before-cursor
+  end:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next *before-cursor
   <span class="Delimiter">{</span>
     at-start-of-text?:boolean<span class="Special"> &lt;- </span>equal start, init
     <span class="muControl">break-if</span> at-start-of-text?
@@ -1600,7 +1602,7 @@ def]
     <span class="muControl">loop</span>
   <span class="Delimiter">}</span>
   <span class="Comment"># snip it out</span>
-  result:address:duplex-list:character<span class="Special"> &lt;- </span>next start
+  result:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next start
   remove-between start, end
   <span class="Comment"># adjust cursor</span>
   *before-cursor<span class="Special"> &lt;- </span>copy start
@@ -1611,16 +1613,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-start-of-line-with-ctrl-u-2 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start on first line (no newline before), press ctrl-u</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">2</span>
     press ctrl-u
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes to start of line</span>
   screen-should-contain [
@@ -1634,16 +1636,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-start-of-line-with-ctrl-u-3 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start past end of line, press ctrl-u</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">3</span>
     press ctrl-u
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes to start of line</span>
   screen-should-contain [
@@ -1657,16 +1659,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-start-of-final-line-with-ctrl-u [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start past end of final line, press ctrl-u</span>
   assume-console [
     left-click <span class="Constant">2</span>, <span class="Constant">3</span>
     press ctrl-u
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes to start of line</span>
   screen-should-contain [
@@ -1682,16 +1684,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-end-of-line-with-ctrl-k [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start on first line, press ctrl-k</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">1</span>
     press ctrl-k
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes to end of line</span>
   screen-should-contain [
@@ -1708,19 +1710,19 @@ def]
     delete-to-end-of-line?:boolean<span class="Special"> &lt;- </span>equal *c, <span class="Constant">11/ctrl-k</span>
     <span class="muControl">break-unless</span> delete-to-end-of-line?
 <span class="Constant">    &lt;delete-to-end-of-line-begin&gt;</span>
-    deleted-cells:address:duplex-list:character<span class="Special"> &lt;- </span>delete-to-end-of-line editor
+    deleted-cells:address:shared:duplex-list:character<span class="Special"> &lt;- </span>delete-to-end-of-line editor
 <span class="Constant">    &lt;delete-to-end-of-line-end&gt;</span>
     go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">1/true</span>
     <span class="muControl">reply</span>
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">recipe</span> delete-to-end-of-line editor:address:editor-data<span class="muRecipe"> -&gt; </span>result:address:duplex-list:character, editor:address:editor-data [
+<span class="muRecipe">recipe</span> delete-to-end-of-line editor:address:shared:editor-data<span class="muRecipe"> -&gt; </span>result:address:shared:duplex-list:character, editor:address:shared:editor-data [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   <span class="Comment"># compute range to delete</span>
-  start:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">before-cursor:offset</span>
-  end:address:duplex-list:character<span class="Special"> &lt;- </span>next start
+  start:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">before-cursor:offset</span>
+  end:address:shared:duplex-list:character<span class="Special"> &lt;- </span>next start
   <span class="Delimiter">{</span>
     at-end-of-text?:boolean<span class="Special"> &lt;- </span>equal end, <span class="Constant">0/null</span>
     <span class="muControl">break-if</span> at-end-of-text?
@@ -1737,16 +1739,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-end-of-line-with-ctrl-k-2 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start on second line (no newline after), press ctrl-k</span>
   assume-console [
     left-click <span class="Constant">2</span>, <span class="Constant">1</span>
     press ctrl-k
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes to end of line</span>
   screen-should-contain [
@@ -1760,16 +1762,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-end-of-line-with-ctrl-k-3 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start at end of line</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">2</span>
     press ctrl-k
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes just last character</span>
   screen-should-contain [
@@ -1783,16 +1785,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-end-of-line-with-ctrl-k-4 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start past end of line</span>
   assume-console [
     left-click <span class="Constant">1</span>, <span class="Constant">3</span>
     press ctrl-k
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes nothing</span>
   screen-should-contain [
@@ -1806,16 +1808,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-end-of-line-with-ctrl-k-5 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start at end of text</span>
   assume-console [
     left-click <span class="Constant">2</span>, <span class="Constant">2</span>
     press ctrl-k
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes just the final character</span>
   screen-should-contain [
@@ -1829,16 +1831,16 @@ def]
 
 <span class="muScenario">scenario</span> editor-deletes-to-end-of-line-with-ctrl-k-6 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[123</span>
 <span class="Constant">456]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   <span class="Comment"># start past end of text</span>
   assume-console [
     left-click <span class="Constant">2</span>, <span class="Constant">3</span>
     press ctrl-k
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># cursor deletes nothing</span>
   screen-should-contain [
@@ -1856,11 +1858,11 @@ def]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># initialize editor with &gt;3 lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .a         .</span>
@@ -1873,7 +1875,7 @@ def]
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen slides by one line</span>
   screen-should-contain [
@@ -1886,11 +1888,11 @@ def]
 
 <span class="muRecipe">after</span> <span class="Constant">&lt;scroll-down&gt;</span> [
   trace <span class="Constant">10</span>, <span class="Constant">[app]</span>, <span class="Constant">[scroll down]</span>
-  top-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
+  top-of-screen:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
   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>
   max:number<span class="Special"> &lt;- </span>subtract right, left
-  old-top:address:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
+  old-top:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
   *top-of-screen<span class="Special"> &lt;- </span>before-start-of-next-line *top-of-screen, max
   no-movement?:boolean<span class="Special"> &lt;- </span>equal old-top, *top-of-screen
   go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
@@ -1900,11 +1902,11 @@ def]
 <span class="Comment"># takes a pointer into the doubly-linked list, scans ahead at most 'max'</span>
 <span class="Comment"># positions until the next newline</span>
 <span class="Comment"># beware: never return null pointer.</span>
-<span class="muRecipe">recipe</span> before-start-of-next-line original:address:duplex-list:character, max:number<span class="muRecipe"> -&gt; </span>curr:address:duplex-list:character [
+<span class="muRecipe">recipe</span> before-start-of-next-line original:address:shared:duplex-list:character, max:number<span class="muRecipe"> -&gt; </span>curr:address:shared:duplex-list:character [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   count:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
-  curr:address:duplex-list:character<span class="Special"> &lt;- </span>copy original
+  curr:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy original
   <span class="Comment"># skip the initial newline if it exists</span>
   <span class="Delimiter">{</span>
     c:character<span class="Special"> &lt;- </span>get *curr, <span class="Constant">value:offset</span>
@@ -1933,11 +1935,11 @@ def]
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># initialize editor with a long, wrapped line and more than a screen of</span>
   <span class="Comment"># other lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef</span>
 <span class="Constant">g</span>
 <span class="Constant">h</span>
 <span class="Constant">i]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .abcd↩     .</span>
@@ -1950,7 +1952,7 @@ def]
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows partial wrapped line</span>
   screen-should-contain [
@@ -1965,18 +1967,18 @@ def]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># editor starts with a long line wrapping twice</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdefghij</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdefghij</span>
 <span class="Constant">k</span>
 <span class="Constant">l</span>
 <span class="Constant">m]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   <span class="Comment"># position cursor at last line, then try to move further down</span>
   assume-console [
     left-click <span class="Constant">3</span>, <span class="Constant">0</span>
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows partial wrapped line containing a wrap icon</span>
   screen-should-contain [
@@ -1990,7 +1992,7 @@ def]
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows partial wrapped line</span>
   screen-should-contain [
@@ -2005,19 +2007,19 @@ def]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">5/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># editor contains a long line in the third line</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">cdef]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   <span class="Comment"># position cursor at end, type a character</span>
   assume-console [
     left-click <span class="Constant">3</span>, <span class="Constant">4</span>
     type <span class="Constant">[g]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># screen scrolls</span>
   screen-should-contain [
@@ -2035,19 +2037,19 @@ def]
 <span class="muScenario">scenario</span> editor-scrolls-down-on-newline [
   assume-screen <span class="Constant">5/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># position cursor after last line and type newline</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   assume-console [
     left-click <span class="Constant">3</span>, <span class="Constant">4</span>
     type [
 ]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># screen scrolls</span>
   screen-should-contain [
@@ -2066,19 +2068,19 @@ def]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">5/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># editor contains a wrapped line</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">cdefgh]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   <span class="Comment"># position cursor at end of screen and try to move right</span>
   assume-console [
     left-click <span class="Constant">3</span>, <span class="Constant">3</span>
     press right-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># screen scrolls</span>
   screen-should-contain [
@@ -2097,20 +2099,20 @@ def]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">5/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># editor contains more lines than can fit on screen</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   <span class="Comment"># position cursor at end of screen and try to move right</span>
   assume-console [
     left-click <span class="Constant">3</span>, <span class="Constant">3</span>
     press right-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># screen scrolls</span>
   screen-should-contain [
@@ -2127,10 +2129,10 @@ def]
 
 <span class="muScenario">scenario</span> editor-scrolls-at-end-on-down-arrow [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abc</span>
 <span class="Constant">de]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
 <span class="Constant">  $clear-trace</span>
   <span class="Comment"># try to move down past end of text</span>
   assume-console [
@@ -2138,9 +2140,9 @@ def]
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># screen should scroll, moving cursor to end of text</span>
   memory-should-contain [
@@ -2151,7 +2153,7 @@ def]
     type <span class="Constant">[0]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2166,9 +2168,9 @@ def]
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># screen stops scrolling because cursor is already at top</span>
   memory-should-contain [
@@ -2180,7 +2182,7 @@ def]
     type <span class="Constant">[1]</span>
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2194,14 +2196,14 @@ def]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># initialize editor with a few pages of lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c</span>
 <span class="Constant">d</span>
 <span class="Constant">e</span>
 <span class="Constant">f</span>
 <span class="Constant">g]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   <span class="Comment"># scroll down one page and one line</span>
   assume-console [
     press page-down
@@ -2209,7 +2211,7 @@ def]
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen scrolls down 3 lines</span>
   screen-should-contain [
@@ -2226,11 +2228,11 @@ def]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># initialize editor with &gt;3 lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .a         .</span>
@@ -2243,7 +2245,7 @@ def]
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen slides by one line</span>
   screen-should-contain [
@@ -2256,8 +2258,8 @@ def]
 
 <span class="muRecipe">after</span> <span class="Constant">&lt;scroll-up&gt;</span> [
   trace <span class="Constant">10</span>, <span class="Constant">[app]</span>, <span class="Constant">[scroll up]</span>
-  top-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
-  old-top:address:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
+  top-of-screen:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
+  old-top:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
   *top-of-screen<span class="Special"> &lt;- </span>before-previous-line *top-of-screen, editor
   no-movement?:boolean<span class="Special"> &lt;- </span>equal old-top, *top-of-screen
   go-render?<span class="Special"> &lt;- </span>copy <span class="Constant">0/false</span>
@@ -2267,7 +2269,7 @@ def]
 <span class="Comment"># takes a pointer into the doubly-linked list, scans back to before start of</span>
 <span class="Comment"># previous *wrapped* line</span>
 <span class="Comment"># beware: never return null pointer</span>
-<span class="muRecipe">recipe</span> before-previous-line curr:address:duplex-list:character, editor:address:editor-data<span class="muRecipe"> -&gt; </span>curr:address:duplex-list:character [
+<span class="muRecipe">recipe</span> before-previous-line curr:address:shared:duplex-list:character, editor:address:shared:editor-data<span class="muRecipe"> -&gt; </span>curr:address:shared:duplex-list:character [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   c:character<span class="Special"> &lt;- </span>get *curr, <span class="Constant">value:offset</span>
@@ -2277,12 +2279,12 @@ def]
   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>
   max-line-length:number<span class="Special"> &lt;- </span>subtract right, left, <span class="Constant">-1/exclusive-right</span>, <span class="Constant">1/wrap-icon</span>
-  sentinel:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
+  sentinel:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">data:offset</span>
   len:number<span class="Special"> &lt;- </span>previous-line-length curr, sentinel
   <span class="Delimiter">{</span>
     <span class="muControl">break-if</span> len
     <span class="Comment"># empty line; just skip this newline</span>
-    prev:address:duplex-list:character<span class="Special"> &lt;- </span>prev curr
+    prev:address:shared:duplex-list:character<span class="Special"> &lt;- </span>prev curr
     <span class="muControl">reply-unless</span> prev, curr
     <span class="muControl">reply</span> prev
   <span class="Delimiter">}</span>
@@ -2298,7 +2300,7 @@ def]
   <span class="Delimiter">{</span>
     done?:boolean<span class="Special"> &lt;- </span>greater-or-equal count, max
     <span class="muControl">break-if</span> done?
-    prev:address:duplex-list:character<span class="Special"> &lt;- </span>prev curr
+    prev:address:shared:duplex-list:character<span class="Special"> &lt;- </span>prev curr
     <span class="muControl">break-unless</span> prev
     curr<span class="Special"> &lt;- </span>copy prev
     count<span class="Special"> &lt;- </span>add count, <span class="Constant">1</span>
@@ -2312,11 +2314,11 @@ def]
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># initialize editor with a long, wrapped line and more than a screen of</span>
   <span class="Comment"># other lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef</span>
 <span class="Constant">g</span>
 <span class="Constant">h</span>
 <span class="Constant">i]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .abcd↩     .</span>
@@ -2328,7 +2330,7 @@ def]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2341,7 +2343,7 @@ def]
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows partial wrapped line</span>
   screen-should-contain [
@@ -2356,17 +2358,17 @@ def]
   <span class="Comment"># screen has 1 line for menu + 4 lines</span>
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">5/height</span>
   <span class="Comment"># editor starts with a long line wrapping twice, occupying 3 of the 4 lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdefghij</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdefghij</span>
 <span class="Constant">k</span>
 <span class="Constant">l</span>
 <span class="Constant">m]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   <span class="Comment"># position cursor at top of second page</span>
   assume-console [
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2380,7 +2382,7 @@ def]
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows partial wrapped line</span>
   screen-should-contain [
@@ -2395,7 +2397,7 @@ def]
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows partial wrapped line</span>
   screen-should-contain [
@@ -2410,7 +2412,7 @@ def]
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows partial wrapped line</span>
   screen-should-contain [
@@ -2429,11 +2431,11 @@ def]
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># initialize editor with a long, wrapped line and more than a screen of</span>
   <span class="Comment"># other lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcdef</span>
 <span class="Constant">g</span>
 <span class="Constant">h</span>
 <span class="Constant">i]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">6/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">6/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .abcde↩    .</span>
@@ -2445,7 +2447,7 @@ def]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2458,7 +2460,7 @@ def]
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows partial wrapped line</span>
   screen-should-contain [
@@ -2473,18 +2475,18 @@ def]
 <span class="muScenario">scenario</span> editor-scrolls-up-past-wrapped-line-using-arrow-keys-4 [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># initialize editor with some lines around an empty line</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 
 c
 d
 e]
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">6/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">6/right</span>
   assume-console [
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2496,7 +2498,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2508,7 +2510,7 @@ e]
     press page-up
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2522,18 +2524,18 @@ e]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">5/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># editor contains &gt;3 lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c</span>
 <span class="Constant">d</span>
 <span class="Constant">e]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">5/right</span>
   <span class="Comment"># position cursor at top of second page</span>
   assume-console [
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .     .</span>
@@ -2546,9 +2548,9 @@ e]
     press left-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
-    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-row:offset</span>
-    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:editor-data, <span class="Constant">cursor-column:offset</span>
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
+    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-row:offset</span>
+    <span class="Constant">4</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">2</span>:address:shared:editor-data, <span class="Constant">cursor-column:offset</span>
   ]
   <span class="Comment"># screen scrolls</span>
   screen-should-contain [
@@ -2567,11 +2569,11 @@ e]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># initialize editor with &gt;3 lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .a         .</span>
@@ -2586,7 +2588,7 @@ e]
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen slides by one line</span>
   screen-should-contain [
@@ -2600,7 +2602,7 @@ e]
     press up-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen remains unchanged</span>
   screen-should-contain [
@@ -2615,11 +2617,11 @@ e]
 
 <span class="muScenario">scenario</span> editor-can-scroll [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .a         .</span>
@@ -2631,7 +2633,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows next page</span>
   screen-should-contain [
@@ -2646,8 +2648,8 @@ e]
   <span class="Delimiter">{</span>
     page-down?:boolean<span class="Special"> &lt;- </span>equal *c, <span class="Constant">6/ctrl-f</span>
     <span class="muControl">break-unless</span> page-down?
-    top-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
-    old-top:address:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
+    top-of-screen:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
+    old-top:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
 <span class="Constant">    &lt;move-cursor-begin&gt;</span>
     page-down editor
     undo-coalesce-tag:number<span class="Special"> &lt;- </span>copy <span class="Constant">0/never</span>
@@ -2662,8 +2664,8 @@ e]
   <span class="Delimiter">{</span>
     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?
-    top-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
-    old-top:address:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
+    top-of-screen:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
+    old-top:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
 <span class="Constant">    &lt;move-cursor-begin&gt;</span>
     page-down editor
     undo-coalesce-tag:number<span class="Special"> &lt;- </span>copy <span class="Constant">0/never</span>
@@ -2676,14 +2678,14 @@ e]
 
 <span class="Comment"># page-down skips entire wrapped lines, so it can't scroll past lines</span>
 <span class="Comment"># taking up the entire screen</span>
-<span class="muRecipe">recipe</span> page-down editor:address:editor-data<span class="muRecipe"> -&gt; </span>editor:address:editor-data [
+<span class="muRecipe">recipe</span> page-down editor:address:shared:editor-data<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   <span class="Comment"># if editor contents don't overflow screen, do nothing</span>
-  bottom-of-screen:address:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">bottom-of-screen:offset</span>
+  bottom-of-screen:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get *editor, <span class="Constant">bottom-of-screen:offset</span>
   <span class="muControl">reply-unless</span> bottom-of-screen
   <span class="Comment"># if not, position cursor at final character</span>
-  before-cursor:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
+  before-cursor:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">before-cursor:offset</span>
   *before-cursor<span class="Special"> &lt;- </span>prev bottom-of-screen
   <span class="Comment"># keep one line in common with previous page</span>
   <span class="Delimiter">{</span>
@@ -2694,16 +2696,16 @@ e]
   <span class="Delimiter">}</span>
   <span class="Comment"># move cursor and top-of-screen to start of that line</span>
   move-to-start-of-line editor
-  top-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
+  top-of-screen:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
   *top-of-screen<span class="Special"> &lt;- </span>copy *before-cursor
 ]
 
 <span class="muScenario">scenario</span> editor-does-not-scroll-past-end [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
-  editor-render screen, <span class="Constant">2</span>:address:editor-data
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  editor-render screen, <span class="Constant">2</span>:address:shared:editor-data
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .a         .</span>
@@ -2715,7 +2717,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen remains unmodified</span>
   screen-should-contain [
@@ -2730,11 +2732,11 @@ e]
   <span class="Comment"># screen has 1 line for menu + 3 lines for text</span>
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># editor contains a long last line</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">cdefgh]</span>
   <span class="Comment"># editor screen triggers wrap of last line</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
   <span class="Comment"># some part of last line is not displayed</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2747,7 +2749,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows entire wrapped line</span>
   screen-should-contain [
@@ -2763,9 +2765,9 @@ e]
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># editor contains a very long line that occupies last two lines of screen</span>
   <span class="Comment"># and still has something left over</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">bcdefgh]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
   <span class="Comment"># some part of last line is not displayed</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2778,7 +2780,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows entire wrapped line</span>
   screen-should-contain [
@@ -2793,11 +2795,11 @@ e]
 
 <span class="muScenario">scenario</span> editor-can-scroll-up [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c</span>
 <span class="Constant">d]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .a         .</span>
@@ -2809,7 +2811,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows next page</span>
   screen-should-contain [
@@ -2823,7 +2825,7 @@ e]
     press page-up
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows original page again</span>
   screen-should-contain [
@@ -2838,8 +2840,8 @@ e]
   <span class="Delimiter">{</span>
     page-up?:boolean<span class="Special"> &lt;- </span>equal *c, <span class="Constant">2/ctrl-b</span>
     <span class="muControl">break-unless</span> page-up?
-    top-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
-    old-top:address:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
+    top-of-screen:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
+    old-top:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
 <span class="Constant">    &lt;move-cursor-begin&gt;</span>
     editor<span class="Special"> &lt;- </span>page-up editor, screen-height
     undo-coalesce-tag:number<span class="Special"> &lt;- </span>copy <span class="Constant">0/never</span>
@@ -2854,8 +2856,8 @@ e]
   <span class="Delimiter">{</span>
     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?
-    top-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
-    old-top:address:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
+    top-of-screen:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
+    old-top:address:shared:duplex-list:character<span class="Special"> &lt;- </span>copy *top-of-screen
 <span class="Constant">    &lt;move-cursor-begin&gt;</span>
     editor<span class="Special"> &lt;- </span>page-up editor, screen-height
     undo-coalesce-tag:number<span class="Special"> &lt;- </span>copy <span class="Constant">0/never</span>
@@ -2867,16 +2869,16 @@ e]
   <span class="Delimiter">}</span>
 ]
 
-<span class="muRecipe">recipe</span> page-up editor:address:editor-data, screen-height:number<span class="muRecipe"> -&gt; </span>editor:address:editor-data [
+<span class="muRecipe">recipe</span> page-up editor:address:shared:editor-data, screen-height:number<span class="muRecipe"> -&gt; </span>editor:address:shared:editor-data [
   <span class="Constant">local-scope</span>
   <span class="Constant">load-ingredients</span>
   max:number<span class="Special"> &lt;- </span>subtract screen-height, <span class="Constant">1/menu-bar</span>, <span class="Constant">1/overlapping-line</span>
   count:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
-  top-of-screen:address:address:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
+  top-of-screen:address:address:shared:duplex-list:character<span class="Special"> &lt;- </span>get-address *editor, <span class="Constant">top-of-screen:offset</span>
   <span class="Delimiter">{</span>
     done?:boolean<span class="Special"> &lt;- </span>greater-or-equal count, max
     <span class="muControl">break-if</span> done?
-    prev:address:duplex-list:character<span class="Special"> &lt;- </span>before-previous-line *top-of-screen, editor
+    prev:address:shared:duplex-list:character<span class="Special"> &lt;- </span>before-previous-line *top-of-screen, editor
     <span class="muControl">break-unless</span> prev
     *top-of-screen<span class="Special"> &lt;- </span>copy prev
     count<span class="Special"> &lt;- </span>add count, <span class="Constant">1</span>
@@ -2888,7 +2890,7 @@ e]
   <span class="Comment"># screen has 1 line for menu + 3 lines</span>
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># initialize editor with 8 lines</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">c</span>
 <span class="Constant">d</span>
@@ -2896,7 +2898,7 @@ e]
 <span class="Constant">f</span>
 <span class="Constant">g</span>
 <span class="Constant">h]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">10/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .a         .</span>
@@ -2909,7 +2911,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows third page</span>
   screen-should-contain [
@@ -2923,7 +2925,7 @@ e]
     press page-up
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows second page</span>
   screen-should-contain [
@@ -2937,7 +2939,7 @@ e]
     press page-up
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows original page again</span>
   screen-should-contain [
@@ -2952,7 +2954,7 @@ e]
   <span class="Comment"># screen has 1 line for menu + 5 lines for text</span>
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">6/height</span>
   <span class="Comment"># editor contains a long line in the first page</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">b</span>
 <span class="Constant">cdefgh</span>
 <span class="Constant">i</span>
@@ -2963,7 +2965,7 @@ e]
 <span class="Constant">n</span>
 <span class="Constant">o]</span>
   <span class="Comment"># editor screen triggers wrap of last line</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
   <span class="Comment"># some part of last line is not displayed</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -2980,7 +2982,7 @@ e]
     press down-arrow
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows entire wrapped line</span>
   screen-should-contain [
@@ -2996,7 +2998,7 @@ e]
     press page-up
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen resets</span>
   screen-should-contain [
@@ -3014,9 +3016,9 @@ e]
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># editor contains a very long line that occupies last two lines of screen</span>
   <span class="Comment"># and still has something left over</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[a</span>
 <span class="Constant">bcdefgh]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
   <span class="Comment"># some part of last line is not displayed</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -3029,7 +3031,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen shows entire wrapped line</span>
   screen-should-contain [
@@ -3043,7 +3045,7 @@ e]
     press page-up
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   <span class="Comment"># screen resets</span>
   screen-should-contain [
@@ -3057,7 +3059,7 @@ e]
 <span class="muScenario">scenario</span> editor-can-scroll-up-past-nonempty-lines [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># text with empty line in second screen</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[axx</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[axx</span>
 <span class="Constant">bxx</span>
 <span class="Constant">cxx</span>
 <span class="Constant">dxx</span>
@@ -3066,7 +3068,7 @@ e]
 <span class="Constant">gxx</span>
 <span class="Constant">hxx</span>
 <span class="Constant">]</span>
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .axx       .</span>
@@ -3077,7 +3079,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -3089,7 +3091,7 @@ e]
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -3102,7 +3104,7 @@ e]
     press page-up
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -3115,7 +3117,7 @@ e]
 <span class="muScenario">scenario</span> editor-can-scroll-up-past-empty-lines [
   assume-screen <span class="Constant">10/width</span>, <span class="Constant">4/height</span>
   <span class="Comment"># text with empty line in second screen</span>
-  <span class="Constant">1</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[axy</span>
+  <span class="Constant">1</span>:address:shared:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[axy</span>
 <span class="Constant">bxy</span>
 <span class="Constant">cxy</span>
 
@@ -3124,7 +3126,7 @@ exy
 fxy
 gxy
 ]
-  <span class="Constant">2</span>:address:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:array:character, screen:address:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
+  <span class="Constant">2</span>:address:shared:editor-data<span class="Special"> &lt;- </span>new-editor <span class="Constant">1</span>:address:shared:array:character, screen:address:shared:screen, <span class="Constant">0/left</span>, <span class="Constant">4/right</span>
   screen-should-contain [
    <span class="Constant"> .          .</span>
    <span class="Constant"> .axy       .</span>
@@ -3135,7 +3137,7 @@ gxy
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -3147,7 +3149,7 @@ gxy
     press page-down
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>
@@ -3160,7 +3162,7 @@ gxy
     press page-up
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, <span class="Constant">2</span>:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, <span class="Constant">2</span>:address:shared:editor-data
   ]
   screen-should-contain [
    <span class="Constant"> .          .</span>