CWnd::FromHandle的解释是:
Returns a pointer to a CWnd object when given a handle to a window. If a CWnd object is not attached to the handle, a temporary CWnd object is created and attached. 当为窗口定义句柄时返回一个指针给CWnd对象.如果CWnd对象没有附着句柄, 则临时CWnd对象被创建.
CWnd::FromHandle(adsw_acadMainWnd())只是明确指出了所创建的Dialog的父窗体是 AutoCAD Main Frame?
大概就这样吧!