Overlapping GdkWindow

[Cédric Lucantis <omer no-log org>]

Hi!

I would like to known how Gdk handles the exposition of overlapping
windows or in other words: how does it 'knows' that a particular
region of a window is obscured by another window and should not be
redrawn? I had a look at the source code and think I understood how
works the invalidate/expose mechanism but did not find anything
related to this. (only the children region are removed from the invalid
area in gdk_window_invalidate(), but nothing about 'sisters' or other
parents)

Sorry if this is not very clear, my english is not good enough:) I
have no real problem with Gtk, I just want to understand how it works.

Explanations or pointers to the relevant parts of the source would be
welcome!

Thanks,
 -- Cédric Lucantis