The PtDivider documentation lists a single Pt_CB_DIVIDER_DRAG callback, but PhAB also lists a 
Pt_CB_DIVIDER_HANDLE_CALLBACK with the text "Drag Handle Callback". Without documentation, I'm at a loss to know what 
the arguments to this callback will be. If I had to guess, I would say two different callbacks were provided to 
distinguish between a drag on the whole PtDivider container and a drag on the handle, and that maybe the documentation 
on Pt_CB_DIVIDER_DRAG actually applies to Pt_CB_DIVIDER_HANDLE_CALLBACK. Is there more information somewhere?