API issue

Theoretically, for a package of library, to the expansion of the API, must be familiar with its structure, find the corresponding position. Even if a statement adds into, also is not literally.
Then, for example as follow, “I want to add a Window without title bar, and enables its to be possible to move along with the mouse .Of course, we must use WM_NCHITTEST”, how should I do?Thank you.
BTW, if I want to modify or change MESSAGE,maybe I can do something,Please give me Suggestions.Thank you very much.

Sorry, your english is just too confused for me to decipher any of that…!

Yep,my english is so so .In other words simply,my question ------how to move a window without title bar,eh do move window in custom area,not on title bar.Maybe it’s just to move a wiondow.

Maybe I can do it,thank you ,jules and everyone.