public void Close()
        {
            _demoBase.CloseDemo();
            _demoBase = null;

            if (_surfaceViewport != null)
            {
                _surfaceViewport.Close();
                _surfaceViewport = null;
            }
            _rootGfx = null;
        }
 public void CloseDemo()
 {
     demobase.CloseDemo();
 }