CWnd::OnWindowPosChanged The framework calls this member function when the size, position, or Z-order has changed as a result of a call to the SetWindowPos member function or another window-management function.Res
The default implementation sends the WM_SIZE and WM_MOVE messages to the window. These messages are not sent if an application handles the OnWindowPosChanged call without calling its base class. It is more efficient to perform any move or size change processing during the call to OnWindowPosChanged without calling its base class. 这个后面才出发WN_SIZE，所以也是无法响应的
The framework calls this member function when the size, position, or Z-order has changed as a result of a call to the SetWindowPos member function or another window-management function.Res
The default implementation sends the WM_SIZE and WM_MOVE messages to the window. These messages are not sent if an application handles the OnWindowPosChanged call without calling its base class. It is more efficient to perform any move or size change processing during the call to OnWindowPosChanged without calling its base class.
这个后面才出发WN_SIZE，所以也是无法响应的