Detect concurrent edits.

dart/site/try/src/ui.dart

 // Copyright (c) 2013, 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.ui;
 
 import 'dart:html';
 
 import 'dart:async' show
     Future,
@@ skipping 30 matching lines @@
     CompilationUnit;
 
 import 'compilation.dart' show
     currentSource;
 
 // TODO(ahe): Make internal to buildUI once all interactions have been moved to
 // the manager.
 InteractionManager interaction;
 
 DivElement mainEditorPane;
+DivElement statusDiv;
 PreElement outputDiv;
 DivElement hackDiv;
 IFrameElement outputFrame;
 MutationObserver observer;
 SpanElement cacheStatusElement;
 Theme currentTheme = Theme.named(theme);
 
 buildButton(message, action) {
   if (message is String) {
     message = new Text(message);
@@ skipping 62 matching lines @@
       ..style.position = 'relative';
 
   var inputHeader = new DivElement()..appendText('Code');
 
   inputHeader.style
       ..right = '3px'
       ..top = '0px'
       ..position = 'absolute';
   inputWrapper.append(inputHeader);
 
+  statusDiv = new DivElement();
+  statusDiv.style
+      ..left = '0px'
+      ..top = '0px'
+      ..position = 'absolute';
+  inputWrapper.append(statusDiv);
+
   outputFrame =
       makeOutputFrame(
           Url.createObjectUrl(new Blob([''], 'application/javascript')));
 
   outputDiv = new PreElement();
   outputDiv.style
       ..backgroundColor = currentTheme.background.color
       ..color = currentTheme.foreground.color
       ..overflow = 'auto'
       ..padding = '1em'
@@ skipping 333 matching lines @@
     window.localStorage['compilationPaused'] = '$compilationPaused';
     window.localStorage['codeFont'] = '$codeFont';
 
     dialog.style.height = '0px';
   }
   form.onSubmit.listen(onSubmit);
 
   var doneButton = document.getElementById('settings-done');
   doneButton.onClick.listen(onSubmit);
 }