gdk-window-clip-region (window)

window -- a gdk-window object

A cairo-region-t structure. This must be freed with the function cairo-region-destroy when you are done.

Computes the region of a window that potentially can be written to by drawing primitives. This region may not take into account other factors such as if the window is obscured by other windows, but no area outside of this region will be affected by drawing primitives.