anchor.diff:        _aceEditor.setOption(
             'enableBasicAutocompletion', path.extension(file.name) != '.dart');
   
  -      // TODO(ericarnold): Markers aren't shown until file is edited.  Fix.
  -      setMarkers(currentFile.getMarkers());
  -
         // Setup handlers once.
         if (_markerSubscription == null) {
           _markerSubscription = file.workspace.onMarkerChange.listen(
               _handleMarkerChange);
  -        currentSession.onChangeFold.listen((_) {
  -          setMarkers(currentFile.getMarkers());
  -        });
         }
       }
     }
  
positive.code:   ace.EditSession get currentSession => _aceEditor.session;
  
    void switchTo(ace.EditSession session, [workspace.File file]) {
      if (session == null) {
        _aceEditor.session = ace.createEditSession('', new ace.Mode('ace/mode/text'));
        _aceEditor.readOnly = true;
  
negative.code:       if (_aceEditor.readOnly) {
          _aceEditor.readOnly = false;
        }
  
        _foldListenerSubscription = currentSession.onChangeFold.listen((_) {
          setMarkers(file.getMarkers());
        });
  
        // TODO(ericarnold): Markers aren't shown until file is edited.  Fix.
        setMarkers(file.getMarkers());
      }
  
      // Setup the code completion options for the current file type.
  