I added a KVM switch to my setup so I can switch between a Windows laptop and an Ubuntu 12.10 desktop. I'm getting a bad resolution through LightDM. The display is huge and I can see that most of it goes off screen so I can't see it. My mouse and keyboard don't work either but that's another problem.
Anyhow, I tried modifying /etc/lightdm/lightdm.conf and added the line
display-setup-script=xrandr --output default --mode 1920x1080
from a different post in hopes that on reboot the problem would get resolved. It didn't make a difference through.
I also tried the instructions by Ghodmode at KVM switch and screen resolution problem and unfortunately this didn't work either.
The way I'm making changes to config files now is via remote desktop into the Ubuntu machine.
One other question - since I'm a noob I don't understand how these pieces all fit together. LightDM is a display manager, is that the same as X? Would making changes to xorg.conf help here?