There are a couple of workarounds though (including one from the bug Alex mentioned) that worked for me.
Initially, I was using the open source "radeon" driver and this worked:
- Edit the file ~/.config/monitors.xml
- You should see configurations listed for both displays. Find the "output" section for the display you want to make primary and look for:
<primary>no</primary> and change it to
- Log out of Unity (or reboot) and log back in.
This, however, did not work for me after I switched to the proprietary "fglrx" driver. Thankfully I found another workaround:
xrandr | grep " connected ". This will give you the names of your connected displays. You should be able to distinguish which display is external from the resolution xrandr reports. In my case it is DPF1.
- to set DFP1 to primary run:
xrandr --output DFP1 --primary