Bug 464207

Summary:	GTK4 programs are not themed to Breeze, when it is selected
Product:	[Plasma] Breeze	Reporter:	Mors Mortium <morsmortium>
Component:	gtk theme	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED DOWNSTREAM
Severity:	normal	CC:	agrinev98, boctorpoo, leguen.yannick, mail, morsmortium, nate, openmail+kde, uhhadd, victorsouzaleal
Priority:	NOR
Version First Reported In:	5.26.4
Target Milestone:	---
Platform:	Manjaro
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Mors Mortium 2023-01-12 17:18:02 UTC

SUMMARY
***
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***


STEPS TO REPRODUCE
1. Install any GTK4 program (gtk4-demos)
2. Choose Breeze as GTK theme
3. Start GTK4 program

OBSERVED RESULT
GTK4 program uses adwaita theme

EXPECTED RESULT
GTK4 program uses Breeze theme

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 5.26.4
KDE Frameworks Version: 5.101.0
Qt Version: 5.15.7

ADDITIONAL INFORMATION
A workaround for this is setting the environment variable ``` GTK_THEME=Breeze ```

Comment 1 Nate Graham 2023-01-12 19:49:50 UTC

Are these apps using libadwaita for their theming, or not?

Comment 2 Mors Mortium 2023-01-12 20:32:40 UTC

The example app (gtk4-demos) does not need libadwaita, and it is reproducible without libadwaita installed. Other GTK4 (not libadawaita) programs, with which this can be reproduced are gtkcord4, vte4.

Comment 3 Nate Graham 2023-01-12 21:26:44 UTC

OK, thanks.

Comment 4 Yannick 2025-10-01 08:56:43 UTC

I can now reproduce this issue on Arch Linux with GTK 4.20.2.

No issue with GTK2 or GTK3 apps, and it didn't happen with GTK 4.18.x

Setting GTK_THEME=Breeze is indeed a valid workaround.

Comment 5 Victor 2025-10-01 12:27:54 UTC

I can reproduce this issue too

Arch Linux / GTK4 4.20.1-1

I had to use the workaround (GTK_THEME=Breeze) manually in GTK4 apps like LACT

Comment 6 Boctor 2025-10-03 01:25:27 UTC

This happens with all GTK4 applications on Wayland for me, too. I am also on Arch.

Only forcing them to run as X clients with GDK_BACKEND makes them respect settings. They do not respect anything configured in $HOME/.config/gtk-4.0/ when running as native Wayland clients. This includes icons, fonts and font sizes, too, which are defaulting back to Cantarell 11 on everything. It seems like the gsettings prefs are also now being ignored by GTK4. I've tried with GTK 4.20.1 and 4.20.2, with no apparent differences.

Comment 7 Mors Mortium 2025-10-03 16:16:26 UTC

https://gitlab.archlinux.org/archlinux/packaging/packages/gtk4/-/issues/14 Possibly related for the Arch users. I am not sure if my issue can be reproduced still, since this happened on Plasma 5 and Manjaro and I use Plasma 6 and Artix now

Comment 8 Yannick 2025-10-03 18:23:00 UTC

(In reply to Mors Mortium from comment #7)
> https://gitlab.archlinux.org/archlinux/packaging/packages/gtk4/-/issues/14
> Possibly related for the Arch users. I am not sure if my issue can be
> reproduced still, since this happened on Plasma 5 and Manjaro and I use
> Plasma 6 and Artix now

I confirm that this was related.
The issue has just been fixed in gtk4 4.20.2-2. Non-libadwaita gtk4 applications now use the Breeze theme (or any other configured theme) as they should.

Comment 9 Mors Mortium 2025-10-03 18:27:40 UTC

Alright, since the recent issue was fixed and the old issue can't be reproduced even by me, the reporter, I'll close this.