I see others have come across this issue, but I can't seem to find a solution. I'm running Ubuntu 16.10 on a Dell Precision 5510. My laptop screen is 4K, and an external monitor is 2560x1440. I'm trying the following:
xrandr --output HDMI-1 --scale 1.7x1.7 --auto --output eDP-1 --scale 0.7x0.7 --left-of HDMI-1
(eDP-1 is the laptop monitor).
This adjusts the resolutions beautifully, but there's this block of area on the right (HDMI-1) monitor that my mouse can't go on. I tried adding --panning 4352x2448 (that's the HDMI's resolution x 1.7), and it kind of works, but then when moving the mouse, it kind of pans the laptop's contents on the HDMI screen. I somehow got this working on Friday, but installed some Ubuntu updates, and can't get it to work as expected any more. Is there a simple trick to enable me to use the mouse on the scaled display?
I'm running xrandr 1.5, if that's useful.
panningparameter. – Afshin Mehrabani Oct 08 '17 at 11:00