Bug 500821

Summary:	Flatpak application font mismatch since KDE 6.3.2
Product:	[Developer tools] Qt/KDE Flatpak Runtime	Reporter:	Jacopo Torrini <jactor>
Component:	general	Assignee:	Aleix Pol <aleixpol>
Status:	RESOLVED FIXED
Severity:	normal	CC:	aacid, john.kizer
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Neon
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:	6.3.3
Sentry Crash Report:
Attachments:	System font settings Betterbird look no flatpak Betterbird with bad looking fonts

Description Jacopo Torrini 2025-02-27 17:27:05 UTC

SUMMARY
After updating to KDE 6.3.2 there is a discrepancy between the fonts rendered by Flatpak applications and the system's defined font preferences, affecting both font family and size.

STEPS TO REPRODUCE
1. Install a flatpak application (in my case Betterbird)
2. Install the same application from another source 
3. Run both applications

OBSERVED RESULT
The fonts in the applications are not consistent with each other

EXPECTED RESULT
The same font in both application 

SOFTWARE/OS VERSIONS

Operating System: KDE neon 6.3
KDE Plasma Version: 6.3.2
KDE Frameworks Version: 6.11.0
Qt Version: 6.8.2
Kernel Version: 6.11.11-061111-generic (64-bit)
Graphics Platform: Wayland

Comment 1 John Kizer 2025-03-05 20:00:13 UTC

Hi - could you please add some information to help this be a bit more specific for folks to try to reproduce:

* What font do you have set that you're expecting to show up in the Flatpak version (and that is appearing in the distribution-packaged version)?
* How specifically do they differ - different typeface, different size, etc.?
* Could you please attach a screenshot from each, if possible?

Thanks!

Comment 2 Jacopo Torrini 2025-03-06 00:07:43 UTC

Created attachment 179161 [details]
System font settings

Comment 3 Jacopo Torrini 2025-03-06 00:10:33 UTC

Created attachment 179162 [details]
Betterbird look no flatpak

This is the standalone version of betterbird that uses my system fonts. The profile used is the same of the flatpack version, so the application specific font is the same.

Comment 4 Jacopo Torrini 2025-03-06 00:11:33 UTC

Created attachment 179163 [details]
Betterbird with bad looking fonts

This is the flatpak version of betterbird. The profile used is the same of the standalone version, so the application specific font is the same.

Comment 5 Jacopo Torrini 2025-03-06 00:14:05 UTC

I've uploaded 3 attachments, one for my system font settings and the other two for betterbird font look.
The good one and the bad one use the same thunderbird profile and the same application settings.

Comment 6 John Kizer 2025-03-06 19:28:28 UTC

Thanks - does the difference persist if you go to a terminal and run flatpak run --command=fc-cache eu.betterbird.Betterbird -f -v (based on https://elementaryos.stackexchange.com/a/29548 ) ?

Comment 7 Jacopo Torrini 2025-03-06 23:52:28 UTC

I ran the command and then launched Betterbird, but the problem persists. 
I've tried a bunch of application both from apt and flatpak and not all applications have this problem:
Whatsapp Desktop (io.github.mimbrero.WhatsAppDesktop) have incorrect fonts.
Xournal++ doesn't.

Comment 8 Jacopo Torrini 2025-03-07 00:39:08 UTC

I've found that if I run Betterbird from commandline I have an error:

flatpak run eu.betterbird.Betterbird 
[2] Wayland Proxy [0x7fd42a787bc0] Error: CheckWaylandDisplay(): Failed to connect to Wayland display '/run/user/1000/wayland-0' error: File o directory non esistente
Error: Failed to open Wayland display, fallback to X11. WAYLAND_DISPLAY='wayland-0' DISPLAY=':1'
Crash Annotation GraphicsCriticalError: |[0][GFX1-]: glxtest: Could not connect to wayland display, WAYLAND_DISPLAY=(null) (t=0.167404) [GFX1-]: glxtest: Could not connect to wayland display, WAYLAND_DISPLAY=(null)
Betterbird: Detected desktop environment kde.

Comment 9 Jacopo Torrini 2025-03-13 15:18:38 UTC

Problem gone in versione 6.3.3 of KDE
Thanks.

Comment 10 John Kizer 2025-03-13 22:23:48 UTC

Glad it's working now!