Wine does not really have it's own API - it's either win32api or POSIX. If you need a "window handle" - you have to run your program under Wine, as those handles exist inside Wine only. You can do lots of things outside Wine as well. Just remember that Wine plays some tricks with X. Oh and Wine have only one big top level window for each .. window. Controls (buttons, text, etc) do not have their own X windows.
