gdk-window-invalidate-region (window region invalidate-children)

window -- a gdk-window object
region -- a cairo-region-t structure
invalidate-children -- true to also invalidate child windows

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 function gdk-window-process-updates sends one or more expose events to the window, which together cover the entire update area. An application would normally redraw the contents of the window in response to those expose events.

GDK will call the function gdk-window-process-all-updates 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 invalidate-children parameter controls whether the region of each child window that intersects region will also be invalidated. If nil, then the update area for child windows will remain unaffected. See the function gdk-window-invalidate-maybe-recurse if you need fine grained control over which children are invalidated.