Cannot switch between light/dark theme in the GNOME session

[Lepaffe Philippe]

In the Ubuntu session, gnome-control-center has an "Appearance" section which allows to switch from Light and Dark themes (which will apply to GTK4 apps as well as set the preference for GTK3 apps), but that section doesn't exist in the control center in the GNOME session.

This means that while you can still choose alternate themes using GNOME Tweaks, they won't properly apply the chosen variant, and by default setting a dark theme will apply that theme's light variant to GTK3 apps while also not switching GTK4 apps to the dark variant of libadwaita.

You can set the which variant with the command line ("gsettings set org.gnome.desktop.interface color-scheme prefer-dark"), but you cannot do this within the UI from the GNOME session like you can from the Ubuntu session.

My understanding is that this stems from the gnome-control-center being in its 41.4 version, with the light/dark switch backported in for the Ubuntu session but not the GNOME session. That in my opinion doesn't make for a great user experience in the GNOME session.
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu82
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: GNOME
DistroRelease: Ubuntu 22.04
InstallationDate: Installed on 2019-12-13 (870 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
Package: gnome-control-center 1:41.4-1ubuntu13
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 5.15.0-27.28-generic 5.15.30
Tags: jammy wayland-session
Uname: Linux 5.15.0-27-generic x86_64
UpgradeStatus: Upgraded to jammy on 2022-04-30 (1 days ago)
UserGroups: adm cdrom dip input libvirt lpadmin lxd plugdev sambashare sudo
_MarkForUpload: True
modified.conffile..etc.default.apport:
 # set this to 0 to disable apport, or to 1 to enable it
 # you can temporarily override this with
 # sudo service apport start force_start=1
 enabled=0
mtime.conffile..etc.default.apport: 2019-12-14T19:11:28.772538

[Chris Guiver (guiverc)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. Please execute the following command only once, as it will automatically gather debugging information, in a terminal:

apport-collect 1971097

When reporting bugs in the future please use apport by using 'ubuntu-bug' and the name of the package affected. You can learn more about this functionality at https://wiki.ubuntu.com/ReportingBugs.

[Lepaffe Philippe (mistermagio)]

apport information

[Lepaffe Philippe (mistermagio)]

apport information

[Lepaffe Philippe (mistermagio)]

apport information

[Jeremy Bícha (jbicha)]

Sorry, this is a WONTFIX for Ubuntu 22.04 LTS. Ubuntu 22.04 LTS uses gnome-control-center 41 which doesn't support setting a theme at all, except in an Ubuntu-specific patch. If you want the Ubuntu experience, use the Ubuntu session. If you want the GNOME experience, use the GNOME session but then you won't get Ubuntu-specific behavior.

This will be fixed in Ubuntu 22.10 which will include gnome-control-center 42 (or probably 43 actually).

I think the best path forward here is for GNOME Tweaks to set the dark color theme preference when setting a dark theme, probably automatically. If that is done, we can backport that bugfix to Ubuntu 22.04 LTS.