Unable to set fractional scaling on three monitor setup

[trozen]

I have three monitors: one 4K (3840x2160) display and two 2560x1440.
I've tried setting fractional scaling to 150% on the 4K display in gnome control center (ubuntu 22.10), but it does not work.

It works fine when I disconnect some displays, leaving only the 4K or 4k and one 2560.
However, when all three are connected the apply button is disabled and the following message appears:
"Changes Cannot be Applied. This could be due to hardware limitations."

When gnome-control-center is started from terminal it shows the following warning:
```
(gnome-control-center:12235): display-cc-panel-WARNING **: 18:42:27.389: Config not applicable: GDBus.Error:org.freedesktop.DBus.Error.InvalidArgs: Logical monitors not adjacent
```
thought it doesn't seem to be the case.

After some digging I've found a workaround, executing the following commands seems to do what the control panel does:
```
xrdb -m <<EOF
Xft.dpi: 192
EOF

xrandr --fb 15360x2880 --dpi 192 --output DP-4 --mode 3840x2160 --panning 5120x2880+0+0 --scale-from 5120x2880 \
    --output DP-2 --mode 2560x1440 --panning 5120x2880+5120+0 --scale-from 5120x2880 --primary \
    --output DP-0 --mode 2560x1440 --panning 5120x2880+10240+0 --scale-from 5120x2880
```

[Alex Wilson (alexwilson1)]

I have the same problem (two 1080p displays and one 3k display). Would that workaround work with wayland?

[Edgar C. (edcolco)]

I have the same problem. Is there an easier way to use fractional scaling when using three screens?

[Edgar C. (edcolco)]

I found this article. I did not work for me completely but it might help someone: https://devicetests.com/set-different-scaling-multi-monitors-gnome

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.