Check if the window and all ancestors of the window are mapped. (This is not necessarily "viewable" in the X sense, since we only check as far as we have GDK window parents, not to the root window.)
TRUE if the window is viewable
Check if the window and all ancestors of the window are mapped. (This is not necessarily "viewable" in the X sense, since we only check as far as we have GDK window parents, not to the root window.)