Qt-Copy causing rendering issues

Fredrik Höglund fredrik at kde.org
Thu Aug 9 23:52:22 BST 2007

On Thursday 09 August 2007 22:33, Robert Knight wrote:
> > What sort of problems?
> It thinks my desktop supports ARGB visuals when it doesn't.  This
> means that where you would normally get a plain color when X erases a
> window surface before drawing on it, I get mostly-black garbage
> instead.  Scrolling performance suffers horribly too.

The X server always supports the ARGB visual when the Composite
extension is enabled, regardless of whether a composition manager
is running or not.

When you're not running a composition manager, these windows are
automatically redirected (redirected to offscreen storage with
automatic updates). But they should be indistinguishable from regular
windows in this case.

That said, I do see the X server occasionally getting confused about
the clip lists, when you have a regular window obscuring an ARGB
window after switching virtual desktops. I'm not seeing the problems
you are describing though, so it may be a problem in the X.org
version you're using, or in the driver.

> What I used to do in Konsole was to check the result of
> KWindowSystem::compositingActive() and only attempting to find a true
> color visual if it returned true.

If applications only select the ARGB visual when a composition
manager is running, you will have to restart all applications that
support transparency after enabling the compositing features
in KWin. It may still be the preferred solution though.


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