VisibilityFullyObscured and Composite...

Roland Mainz roland.mainz at
Tue Oct 19 19:55:14 PDT 2004

Keith Packard wrote:
> > How does the "Composite" extension deal with the
> > "VisibilityFullyObscured" event ? There are some applications which
> > simply stop some activities (like animation playback) when they are
> > fully obscured - which makes sense when the window content is not
> > visible.
> Composite doesn't change the semantics of visibility at all; so
> applications which change their behaviour in the presence of these events
> will probably not work as desired.
> I suspect the best answer we might be able to provide would be to have the
> Composite Manager responsible for computing visibility, but the event
> ordering requirements in the core protocol make that rather impractical.
> Alternatively, we could just make them always unobscured; that should be
> easy.

That may result in performance problems and other unwanted effects. Just
think about TAB widgets where each tab is a subwindow - in that case the
VisibilityFullyObscured event will turn off activities in the full
obscured tabs. Making all windows always unobscured will cause much
trouble as none of the tabs will stop rendering.

What about adding an own event API to the Composite extension that
applications can get events for the case that they are fully obscured
but still visible (througth other transparent windows) ?



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