location to store the drawable to which drawing should be done. out
location to store the X offset between coordinates in window, and the underlying window system primitive coordinates for *real_drawable. out
location to store the Y offset between coordinates in window, and the underlying window system primitive coordinates for *real_drawable. out
there may be an offset between GDK coordinates and windowing system coordinates, and GDK may have redirected drawing to a offscreen pixmap as the result of a gdk_window_begin_paint_region() calls. This function allows retrieving the information you need to compensate for these effects. This function exposes details of the GDK implementation, and is thus likely to change in future releases of GDK.
If you bypass the GDK layer and use windowing system primitives to draw directly onto a GdkWindow, then you need to deal with two