采用子类化技术，拦截ComboList的右键单击事件-The use of sub-class technology, to intercept the right-click events ComboList

在基于对话框的程序中，默认是没有这个消息的，按下Ctrl+W，弹出类向导对话框，选择Class Info标签-Basic implementation of a drop source is relatively simple. The first step is to determine what events begin a drag operation.

没有使用图形文件, 全部自画的按钮开关控件, 并且实现了开关事件-Don t use the graphics file, all the draw button switch control, and realizes the switch events