Comment 10 for bug 1326688

I have this problem on Linux Mint 17.1 (Ubuntu 14.04 base) too on a Lenovo T420s with Optimus graphics using the Nvidia card as primary.

It seems to work as expected if I put the screens in order [LVDS-1-0] -- [VGA-1-0] -- [DP-3] from left to right, but if I put DP-3 in the middle, I can't disable panning for it.

Just putting the screens in this physical order works for me, but I run into another problem when I try to set the middle screen (VGA-1-0) to primary in order to get my KDE taskbar on the middle screen. Trying to set any of the screens provided by modesetting to primary fails with the following error:

  $ xrandr --output VGA-1-0 --primary
X Error of failed request: BadMatch (invalid parameter attributes)
  Major opcode of failed request: 140 (RANDR)
  Minor opcode of failed request: 30 (RRSetOutputPrimary)
  Serial number of failed request: 50
  Current serial number in output stream: 52

  $ xrandr --output LVDS-1-0 --primary
X Error of failed request: BadMatch (invalid parameter attributes)
  Major opcode of failed request: 140 (RANDR)
  Minor opcode of failed request: 30 (RRSetOutputPrimary)
  Serial number of failed request: 50
  Current serial number in output stream: 52

I attach my Xorg configuration (generated by nvidia-settings), the Xorg log file, a dump of 'xrandr --verbose' output and 'xrandr --listproviders' output.