Proper windowed mode support

[[TK!] (´･ω･`)]

Bit of a stretch to hope for something like this to get included (though depending on the engine used or if its just straight up OpenGL calls, shouldn't be hard to enable) but:
Is there any potential to get a proper windowed mode? Right now the best I can get is a no-border windowed mode even when the resolution is set below my monitor. It just fills in the rest of the screen with black nothing.

Also it wrestles control away from my WM in linux, which means I have to open the steam overlay to open a terminal and kill the program since it also refuses to let focus shift.

[Hypertext Eye]

Windowed mode works fine in Windows. I don't know why Linux would be different.