anchor.diff:  
     ace.EditSession get currentSession => _aceEditor.session;
   
  +  // TODO(ericarnold): Deleteme.  testing
  +  static Map<ace.EditSession, String> filenameBySession = {};
  +
     void switchTo(ace.EditSession session, [workspace.File file]) {
       if (_foldListenerSubscription != null) {
         _foldListenerSubscription.cancel();
  
positive.code:       _aceEditor.session = ace.createEditSession('', new ace.Mode('ace/mode/text'));
        _aceEditor.readOnly = true;
      } else {
        _aceEditor.session = session;
  
        if (_aceEditor.readOnly) {
  
negative.code:   }
  
    void _handleMarkerChange(workspace.MarkerChangeEvent event) {
      /*%TRACE3*/ print("(4> 2/1/14): _handleMarkerChange!"); // TRACE%
      if (event.hasChangesFor(currentFile)) {
        setMarkers(currentFile.getMarkers());
      }
  