Problems with the radeon driver

[Adam K Kirchhoff]

Has anyone else seen this type of artefacting with the radeon driver:

http://adam.visualtech.com/radeon-corruption.jpg

I get it on two different machines, one with an HD4850 and one with an HD4350.  
I've put up with it for over a year now, but it's really started to get on my 
nerves.

I've done some testing and it seems to have been introduced in 6.13.0.  If I 
go back to 6.12.7, everything is fine.  I'm using X server 1.7.7 from ports, 
with EXA acceleration.  This happens without a compositor running 
(kwin/compiz/xcompmgr).  In the screenshot, it's just plain openbox.  You can 
see three windows (Terminal, akregator, chrome) as one big giant mess.   This 
happens mostly when moving/resizing windows, but also with scrolling.  

Running 'xrefresh' will clear the screen and redraw everything properly.  But 
then I move a window, and it happens again.  Sometimes it's worse than others.  
In the screenshot, it's particularly bad.

Unfortunately, the developers in #radeon on Freenode don't seem paritcularly 
concerned as this bug is only present when using UMS (I had the same issue in 
Slackware at one point when I was using UMS), and UMS is now, essentially, 
deprecated.

There is at least one bug reported on http://bugs.freedesktop.org/ that seems 
to be related: https://bugs.freedesktop.org/show_bug.cgi?id=27650

Adam