Good news to all Kubuntu and Fedora users. The cause for the video garbage appearing whenever a new window is opened has been discovered. A custom patch to xorg is causing the trouble. Now we can only hope that the distributions will provide updates for xorg without this patch. If you don’t want to wait that long and you are a Kubuntu user just add the following ppa to your sources.list and upgrade your system:
deb http://ppa.launchpad.net/adamspain/ubuntu intrepid main
The interesting thing is that NVIDIA knew about this patch for at least one month and started to work around it in their drivers. That’s great as it shows that they care about KDE and want to improve the KDE experience. The bad is that they did not communicate that a custom patch to xorg is responsible for the problem. Neither in KDE’s nor in Ubuntu’s bug report there is a comment from NVIDIA. And that’s sad. With a little bit more communication the problem would have been solved much earlier.