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!