Bitmap buttons cannot be supported on non-graphical systems. Under such systems, an attempt to create a bitmap button will fail, returning a handle with the value NULL. If you intend to run programs with bitmap buttons on character-based systems, you should arrange your program so that it can run effectively without the bitmap buttons, or substitute regular push buttons for the bitmap buttons when running on character-based systems.
Bitmaps are highly host-system dependent. You should be prepared to recreate or convert your bitmaps when moving to other graphical systems.