中文说明：本例演示：如何依靠图形窗的 UserData 属性传送用户控件的图柄，从而保证回调动作正确执行。-the cases demonstrate : how to rely on the graphics window UserData attributes transmission users control plans handles, callback action so as to ensure correct implementation.
English Description：
the cases demonstrate : how to rely on the graphics window UserData attributes transmission users control plans handles, callback action so as to ensure correct implementation.