Computes the region of the @window that is potentially visible. This does not necessarily take into account if the window is obscured by other windows, but no area outside of this region is visible.
a #cairo_region_t. This must be freed with cairo_region_destroy() when you are done.
See Implementation
Computes the region of the @window that is potentially visible. This does not necessarily take into account if the window is obscured by other windows, but no area outside of this region is visible.