Bug 467207

Summary: Fonts become garbled in GTK apps
Product: [I don't know] kde Reporter: David <david.cortes.rivera>
Component: generalAssignee: Unassigned bugs mailing-list <unassigned-bugs>
Status: RESOLVED DOWNSTREAM    
Severity: normal CC: nate
Priority: NOR    
Version: unspecified   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: Version Fixed In:
Sentry Crash Report:
Attachments: garbled_fonts

Description David 2023-03-11 16:22:32 UTC 
Created attachment 157191 [details]
garbled_fonts

SUMMARY
When using GTK apps like VScode or Vivaldi, the fonts in some places will become garbled at random times (see screenshot for an example in VScode, particularly the part where it's supposed to say "C/C++").

For VScode, this mostly affects the text shown when one clicks on "Settings". Other places like the editor do not suffer from this problem.

For Vivaldi, this affects the names of tabs, but doesn't seem to affect anything else. Happens way more frequently and the garbling is way more noticeable in Vivaldi than in VScode.

I suppose it might be related to this other bug: https://bugs.kde.org/show_bug.cgi?id=464824

STEPS TO REPRODUCE (Vivaldi)
1. Launch Vivaldi.
2. Open many websites in many tabs.
3. Browse some website as usual.
4. Look at the tab bar.

STEPS TO REPRODUCE (VScode)
1. Launch VScode.
2. Click the settings icon at the bottom-right corner in the side panel.
3. Select "Settings" in the pop-up that opens.
4. Search for something in the settings, such as "cwd" or "path".
5. Watch the panel at the left that shows the categories of settings.

OBSERVED RESULT
After a while, fonts in the tab bar become garbled in Vivaldi, and fonts in the settings left panel become garbled in VScode. They fix themselves when making the tab active or passing the mouse over them.

EXPECTED RESULT
Fonts should remain well rendered.

SOFTWARE/OS VERSIONS
Operating System: Debian GNU/Linux 12
KDE Plasma Version: 5.27.2
KDE Frameworks Version: 5.103.0
Qt Version: 5.15.8
Kernel Version: 6.1.0-6-amd64 (64-bit)
Graphics Platform: X11
Processors: 20 × 12th Gen Intel® Core™ i7-12700H
Memory: 62.5 GiB of RAM
Graphics Processor: Mesa Intel® Graphics
Manufacturer: SLIMBOOK
Product Name: Executive

ADDITIONAL INFORMATION
Comment 1 Nate Graham 2023-03-13 20:28:51 UTC 
Bug 464824 seems like something else; this issue here seems like it's an issue with the rendering engine used by those apps. It might even be  a GPU driver issue.

Either way, there's no KDE code used to draw these strings of text. I'd recommend following up with your distro, GPU driver devs, or GTK devs (in that order).
Comment 2 David 2023-03-16 16:59:43 UTC 
(In reply to Nate Graham from comment #1)
> Bug 464824 seems like something else; this issue here seems like it's an
> issue with the rendering engine used by those apps. It might even be  a GPU
> driver issue.
> 
> Either way, there's no KDE code used to draw these strings of text. I'd
> recommend following up with your distro, GPU driver devs, or GTK devs (in
> that order).

By the way, while not solved entirely, I notice this bug happens way less frequently if I reset the font settings through gnome-tweaks. From bug report 464824, I understand those are partially controlled by KDE so I think this bug could actually be related to something from KDE configs.