Comment # 4 on bug 68585 from Richard Van Den Boom

According to bisect, the commit that cause the crashes is this one :

git bisect good 98d2498404ba69a3efc1c765b1a1885d151181ed
# first bad commit: [a3ae5dc7dd5c2f8893f86a920247e690e550ebd4] draw: make sure
that the stages setup outputs

I've attached the full git bisect log output.
Whatever Kwin does in the R300 driver, the above commit seems to trigger an
issue.