anchor.diff:  
       SparkDialogButton okButton = _okCancelDialog.getElement('#okText');
       _okCancelDialog.getElement('#okText').text = okButtonLabel;
  -
  -    if (okAction != null) {
  -      okButton.onClick.listen((_) {
  -        // Ensures that errorDialog closes before the action.
  -        Timer.run(() {
  -          okAction();
  -        });
  -      });
  -    }
   
       _okCancelCompleter = new Completer();
       _okCancelDialog.show();
  
positive.code: 
    void _handleAuthError(context) {
      String message = 'Authorization error. Bad username or password.';
      Function okAction = () {
        _showAuthDialog(context);
      };
      spark.askUserOkCancel(message,
          okButtonLabel: 'Login Again', title: 'Push failed', okAction: okAction);
    }
  
    void _push() {
  
negative.code:   /**
     * Show a model error dialog.
     */
    void showErrorMessage(String title, String message) {
      // TODO(ussuri): Polymerize.
      if (_errorDialog == null) {
        _errorDialog = createDialog(getDialogElement('#errorDialog'));
  