I have just installed KUbuntu 12.04 (beta), and I can confirm that this bug is gone in this release. I also verified this with the Clemens Eisserer's testcase available in the Freedesktop report (Bug 22566). This testcase no longer leaves any trash on the screen.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/325074 Title: Window redrawing does not work properly with KDE4 taskbar tooltips. To manage notifications about this bug go to: https://bugs.launchpad.net/kde-baseapps/+bug/325074/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
