程序主要完成的功能是：对单文档模式下，添加菜单，并完成响应，达到的目的是，在窗口实现用鼠标完成简单的绘图，类似于画图板-The main function of the completion of the procedure is: for single-document mode, add the menu, and complete response, the purpose is to achieve in the window with the mouse to complete sim