设计一个应用程序，选择菜单项“开始”后红色的小球沿一定方向移动，当碰到边界后小球会反弹，当选择菜单项“停止”后小球停止移动。-Designing an application, select the menu item " Start"　after the red ball moving along a certain direction, when it comes to the border after the ball will bounce, when you select the menu item " Stop"　after the ball stops moving.