Multi-monitor settings are lost when switching between single- and extended-display modes using the keyboard (Super+P) or in gnome-control-center

[Amr Ibrahim]

Bug summary:

I set up and save the two configurations separately in gnome-control-center for single- and extended-display modes, but they are not applied when switching modes with Super+P (or with the dedicated key) or when switching modes in gnome-control-center, the settings don't persist.

The settings are saved in ~/.config/monitors.xml when setting up and saving the configuration in gnome-control-center, but they are not applied when switching with Super+P or when switching modes in gnome-control-center, the settings don't persist.

Another way to see the bug is to save a mode configuration in gnome-control-center then switch to the same mode using Super+P by pressing Super+P many times without selecting a different mode, the settings will be lost. See the attached screencast.

Steps to reproduce:

0. Attach an external monitor to the laptop

1. Change the fractional scaling of the external monitor to 150% and change the positioning of the built-in monitor to the desired positioning

2. Switch to the single-display mode using the keyboard or in gnome-control-center

3. The fractional scaling of the external monitor changes to 100% → (this could be the intended behaviour and not a bug)

4. Change again the fractional scaling of the external monitor to 150%

5. Switch to the extended-display mode using the keyboard or in gnome-control-center

6. The fractional scaling of the external monitor changes to 100% → (this is a bug, it should persist from step 1 or 4)

7. The positioning of the built-in monitor changes to the default → (this is a bug, it should persist from step 1)

What happened:

Multi-monitor settings are lost when switching between single- and extended-display modes.

What I expect to happen:

Multi-monitor settings should persist.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: mutter 3.36.6-1ubuntu0.20.04.2
ProcVersionSignature: Ubuntu 5.4.0-54.60-generic 5.4.65
Uname: Linux 5.4.0-54-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.12
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Fri Nov 20 20:04:26 2020
InstallationDate: Installed on 2020-04-26 (208 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: mutter
UpgradeStatus: No upgrade log present (probably fresh install)

[Daniel van Vugt (vanvugt)]

"Single" and "extended" display modes sound like different configurations. You need to set each up separately with your preferred settings in gnome-control-center, and save the settings of each. If you have done that, and especially if you have verified it's been saved in ~/.config/monitors.xml then this is a bug.

Does it only happen in Wayland sessions?

[Daniel van Vugt (vanvugt)]

I'm assuming you're using the equivalent feature of Super+P. Some models of laptop have a dedicated key to do the same thing.

Looking at gnome-shell's switchMonitor.js it looks pretty simple but I would recommend editing your ~/.config/monitors.xml and ensuring the scaling settings you want are remembered there.

[Amr Ibrahim (amribrahim1987)]

I set up and save the two configurations separately in gnome-control-center, but they are not applied when switching modes with Super+P (or with the dedicated key) or when switching modes in gnome-control-center, the settings don't persist.

The settings are saved in ~/.config/monitors.xml when setting up and saving the configuration in gnome-control-center, but they are not applied when switching with Super+P or when switching modes in gnome-control-center, the settings don't persist.

Another way to see the bug is to save a mode configuration in gnome-control-center then switch to the same mode using Super+P by pressing Super+P many times without selecting a different mode, the settings will be lost. See the attached screencast.

[Amr Ibrahim (amribrahim1987)]

The bug happens in both X11 and Wayland.

[Daniel van Vugt (vanvugt)]

Please open a bug with the developers at:

https://gitlab.gnome.org/GNOME/gnome-shell/-/issues

and tell us the new issue ID.