Comment 14 for bug 290156

I have a kdm specific work around. I added:

xrandr --output VGA --mode 1280x960

to

/etc/kde4/kdm/Xsetup

That particular script runs as root before the login dialogue appears so the settings affect all uses and the login dialogue. All the per user attempts were failing because the login dialogue was still at the wrong resolution. There is still a brief 'out of range' error when the initial wallpaper is shown at full resolution, but then it shifts and login/normal operation follows.