C#按钮式菜单控件和测试源代码ButtonMenuContro_and_Demo，类似outlook样式的按钮菜单控件，包含测试程序的源代码，注意：在测试程序里要定义响应控件的OnMenuButtonClick事件。-C# button menu control and test source code ButtonMenuContro_and_Demo similar outlook style button menu controls, containing test program sou