Window Features（包括Z-Order，Layered Windows, Message-Only Windows, Owned Windows, Window的状态等）

https://msdn.microsoft.com/en-us/library/windows/desktop/ms632599(v=vs.85).aspx#owned_windows

https://msdn.microsoft.com/en-us/library/windows/desktop/ms633515(v=vs.85).aspx

http://www.cnblogs.com/findumars/p/6348012.html