extMenuTool.mouseDownPoint
              )
          ),
          makeButton(
            'Undo',
            (e, obj) => e.diagram.commandHandler.undo(),
            (o) => o.diagram.commandHandler.canUndo()
          ),
          makeButton(
            'Redo',
            (e, obj) => e.diagram.commandHandler.redo(),
            (o) => o.diagram.commandHandler.canRedo()
          )
        ),
      'undoManager.isEnabled': true
    });

    // To simplify this code we define a function for creating a cont