XDamage extension over-reports window damage

[Jonathan Lennox]

On Thursday, January 27 2005, "Owen Taylor" wrote to "Jonathan Lennox, Keith Packard, xorg at lists.freedesktop.org" saying:

> Any impetus for action here is decreased by the move to  Composite that
> is under way. Once we are keeping full contents for all toplevel
> windows, they will never be covered, so tracking that isn't very
> interesting.

For application sharing, there is (potentially) a motivation to keep track
of what the user can actually *see* -- the idea is that if the user covers
up part of a window with another one, the application sharing server
shouldn't send that window part, for privacy reasons.

As Joel Dice mentioned, with the current X protocol, it's possible for a
client to manually track the positions and stacking of all top-level windows
and so compute which parts of the windows of interest are visible to the
user.

Is this possible with the composite extension?  I'm not very familiar with
the details of that.

-- 
Jonathan Lennox
lennox at cs.columbia.edu