可以显示三态的按钮类，可调用其中的函数给其加载位图，三态位图是一个位图，鼠标放上去，鼠标up和鼠标down会加载不同的位图，有动态效果-Can display three-state button category, which can call a function to its load bitmaps, three-state bitmap is a bitmap, release the mouse up, mouse up and mouse down will load differ