public virtual void AddScrollDown(ButtonArea buttonArea)
 {
     buttonArea.SetContentManager(_contentManager);
     buttonArea.SetInputChecker(_inputChecker);
     buttonArea.SetButtonSelectAction(new ScrollDownAction());
     buttonArea.HasShortcutWithMouseWheelDown = true;
     _buttonAreaList.AddScrollDown(buttonArea);
 }
 public virtual void AddButtonArea(ButtonArea buttonArea)
 {
     buttonArea.SetContentManager(_contentManager);
     buttonArea.SetInputChecker(_inputChecker);
     _buttonAreaList.Add(buttonArea);
 }