Only save what's needed.

dart/site/try/src/interaction_manager.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library trydart.interaction_manager;
 
 import 'dart:html';
 
 import 'dart:convert' show
     JSON;
@@ skipping 76 matching lines @@
 
 /**
  * UI interaction manager for the entire application.
  */
 abstract class InteractionManager {
   // Design note: All UI interactions go through one instance of this
   // class. This is by design.
   //
   // Simplicity in UI is in the eye of the beholder, not the implementor. Great
   // 'natural UI' is usually achieved with substantial implementation
-  // complexity that doesn't modularise well and has nasty complicated state
+  // complexity that doesn't modularize well and has nasty complicated state

[ahe, 2014/05/14 11:01:24]

Sometimes I encounter a bug in Chrome and it turns on spellchecking although it
shouldn't.  But it helped me find a typo :-)

   // dependencies.
   //
   // In rare cases, some UI components can be independent of this state
   // machine. For example, animation and auto-save loops.
 
   // Implementation note: The state machine is actually implemented by
   // [InteractionContext], this class represents public event handlers.
 
   factory InteractionManager() => new InteractionContext();
 
@@ skipping 374 matching lines @@
     }
   }
 
   void onHeartbeat(Timer timer) {
     if (context.unitsToSave.isEmpty &&
         context.saveTimer.elapsed > SAVE_INTERVAL) {
       context.saveTimer
           ..stop()
           ..reset();
       context.unitsToSave.addAll(context.modifiedUnits);
+      context.modifiedUnits.clear();
       saveUnits();
     }
     if (!settings.compilationPaused &&
         context.compileTimer.elapsed > COMPILE_INTERVAL) {
       if (startCompilation()) {
         context.compileTimer
             ..stop()
             ..reset();
       }
     }
@@ skipping 462 matching lines @@
   return text.split(new RegExp('^', multiLine: true));
 }
 
 void removeCodeCompletion() {
   List<Node> highlighting =
       mainEditorPane.querySelectorAll('.dart-code-completion');
   for (Element element in highlighting) {
     element.remove();
   }
 }