这是一个悬停位图按钮，在项目开发中有很高的应用价值，该按钮有两种用途，一是给按钮添加４个bitmap实现悬停功能，而是给按钮添加2个bitmap实现单选按钮或复选按钮功能-This is a hovering bitmap buttons, the project is the development of high value, the button for both purposes, One button to add four bitmap achieve hover function,