I have three monitors, all 1920×1200.

I need one monitor (either 2 or 3, above) to use a subset of the pixels, 1624×1092. I need this so that a specific application that launches fullscreen will be exactly that resolution. I don't care where on the monitor this subset is placed; top left is fine.
I've spent an hour chasing down similar questions on various sites, with answers involving xrandr
, but don't see anyone declaring victory. I don't have to use xrandr
, if there's another solution that works.
The output of xrandr
, if it helps:
$ xrandr
Screen 0: minimum 8 x 8, current 5760 x 1200, maximum 32767 x 32767
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 connected primary 1920x1200+3840+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 59.95*+
1600x1200 60.00
1280x1024 75.02 60.02
1152x864 75.00
1024x768 75.03 60.00
800x600 75.00 60.32
640x480 75.00 59.94
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 59.95*+
1600x1200 60.00
1280x1024 75.02 60.02
1152x864 75.00
1024x768 75.03 60.00
800x600 75.00 60.32
640x480 75.00 59.94
DP-4 disconnected (normal left inverted right x axis y axis)
DP-5 connected 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 59.95*+
1600x1200 60.00
1280x1024 75.02 60.02
1152x864 75.00
1024x768 75.03 60.00
800x600 75.00 60.32
640x480 75.00 59.94
This is on Ubuntu 20.04