一个发射按钮可以发射一个弹球，该球遇到边界时会自动弹回，在移动固定次数后，该球停止运动。要求每次点击发射按钮都会发射一个弹球，如果点击多次，则多个弹球同时运动-A launch button to launch a ball, the ball met the boundary will automatically jump back on the move after a fixed number of times the ball stop. Requirements of each click the launch button will launch a ball, if you click several times, the number of marbles at the same time exercise