一般的MFC 创建的单文档或这多文档程序工具栏默认为浮动状态的，即可以自由移动，我们仿照工具栏把菜单栏也做成浮动状态-MFC generally created more than a single document or document procedures for the floating toolbar default state, that is free to move, we modeled the toolbar to create a floating menu bar is