I have following setup:
nvidia optimus laptop (Thinkpad P50), using proprietary nvidia driver
- external 1920x1080 screen connected to nvidia card (DP-3.2 in xrandr), it is positioned left of my 2nd screen
- internal 1920x1080 screen connected to integrated intel card (right of 1st screen) nvidia drivers 367.35-0ubuntu0~gpu16.04.2
- kernel 4.6.6 (from http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.6.6/)
When I boot lightdm sets the screens to clone, which is fine.
After login, or when I connect the external screen and use "Displays" utility to extend the desktop to the monitor, following happens
- external screen to the second screen (the screen "scrolls" when I position the mouse cursor to the right edge) - I had the same issue on 15.10, but it was the only one, I am able to work around this by playing with "Display" utitily (changing orientation, turning screen off etc. could not find a deterministic way to do this)
- maximized windows span both screens
- new windows appear in the centre of the whole desktop, not current monitor (= half on first screen, half on second screen)
None of this happens when I move the internal screen left of the external screen.
My xorg.conf: http://pastebin.com/UmAcNVSy
xrandr -q output: http://pastebin.com/SLJNpZTm