动态菜单的编写，如何让程序在运行时产生新的菜单项及如何手工为这些新产生的菜单命令安排处理函数，如何在顶层窗口中截获对菜单命令的处理，更进一步掌握CString类的应用。-Dynamic menu preparation, how to make the procedures in the run-time generate a new menu item and how to have a manual for these new arrangements to deal with the me