gdk:window-invalidate-maybe-recurse (window region func)

window -- a gdk:window object
region -- a cairo:region-t instance
func -- a gdk:window-child-func callback function to use to decide if to recurse to a child, nil means never recurse

Adds region to the update area for window. The update area is the region that needs to be redrawn, or "dirty region". The call of the gdk:window-process-updates function sends one or more expose events to the window, which together cover the entire update area. An application would normally redraw the contents of window in response to those expose events.

GDK will call the gdk:window-process-all-updates function on your behalf whenever your program returns to the main loop and becomes idle, so normally there is no need to do that manually, you just need to invalidate regions that you know should be redrawn.

The func parameter controls whether the region of each child window that intersects region will also be invalidated. Only children for which func returns true will have the area invalidated.