Version:            (using KDE 4.1.2)
OS:                Linux
Installed from:    Ubuntu Packages

I did the update from Kubuntu Hardy to Ibex and have a problem with the window bar since. When I open a window to compose a message in Mozilla Thunderbird the entries for the applications in my window bar show very strange artefacts. The window bar then looks like this: http://www.bikelab.org/bugs/snap-b.png

When I go over the entries with the mouse pointer a number of entries change unpredictably. Some are blacked out, others reappear or show artefacts instead. Similar problems exist with the digital clock. Here its possible to black it out or make it reappear just by going over it with the mouse pointer. The bug is reproducable here at all times, but it only happens when a window for composing a message in Mozilla Thunderbird is open.

If you think KDE general is the wrong category for this bug please correct it. I asked in a German Ubuntu forum which component to file this bug against but did not get an answer (http://forum.ubuntuusers.de/topic/darstellungsprobleme-in-kde-fensterleiste/). However, there was one answer from a user who said that he and and one of his fellows also have this problem, but with Gnome. He also wrote that he tried the alternative nvidia driver which did not help.