Created attachment 32064 [details]
Xorg.0.log

I've got two computers with persistent repainting problems.  Not sure if this is a KDE problem or an X.Org problem.  Both machines are x86-64 systems running openSUSE 11.2, KDE 4.3.4 (though the problem has occurred with all KDE 4.x versions), and X.Org 7.4, all installed from openSUSE 11.2 RPMs.  However, they have different video cards:  in one case an Nvidia Quadro NVS 140M (using the proprietary nvidia-gfxG02 driver) and in the other an Intel 965 GM (using the "intel" driver).

Reproducibility: Usually, but not always

Steps to reproduce:
1. Hover the mouse pointer over something which causes a tooltip window to pop up.  This could be something in the KDE panel (like the task bar or system tray), or a web page link with a "title" attribute in a web browser.
2. Move the mouse pointer off the widget.  The bug can be more reliably reproduced if this is done by using the mouse scroll wheel to scroll the window contents up or down.

Observed behaviour:
3. Either:
  a) Once the mouse pointer is moved off the widget, the tooltip window disappears, but what's underneath gets repainted with a solid colour or the desktop background.
  b) Once the mouse pointer is moved off the widget, the tooltip window disappears, and what's underneath gets properly repainted, but some other area of the screen suddenly gets painted with the desktop background image.
  c) Once the mouse pointer is moved off the widget, the tooltip window disappears, and what's underneath gets properly repainted.  However, the next time a tooltip window is created, some other area of the screen suddenly gets painted with the desktop background image.