Bug 496012

Summary: Web Browser plasmoid and KHelpCenter's QtWebEngine does not adhere to the Fonts KCM's preferences.
Product: [Unmaintained] kdeplasma-addons Reporter: Roke Julian Lockhart Beedell <4wy78uwh>
Component: Web BrowserAssignee: Plasma Bugs List <plasma-bugs>
Status: RESOLVED UPSTREAM    
Severity: wishlist CC: nate
Priority: NOR    
Version First Reported In: 6.2.2   
Target Milestone: ---   
Platform: Fedora RPMs   
OS: Linux   
URL: https://bugreports.qt.io/browse/QTBUG-131844
See Also: https://bugs.kde.org/show_bug.cgi?id=496990
Latest Commit: Version Fixed In:
Sentry Crash Report:
Attachments: Screenshot of the Web Browser plasmoid at a "file"-schema URI.
Screenshot of the "Fonts" KCM.

Description Roke Julian Lockhart Beedell 2024-11-09 15:31:05 UTC 
Created attachment 175679 [details]
Screenshot of the Web Browser plasmoid at a "file"-schema URI.

SUMMARY
-------
My `kcm_fonts` font preferences are not applied to Web Browser's embedded Chromium instance.

STEPS TO REPRODUCE
------------------
1. Add the Web Browser plasmoid to the `plasmashell` desktop.
2. Render any HTML file (at any URI) that doesn't explicitly define a font.

OBSERVED RESULT
---------------
My `kcm_fonts` font preferences are not applied to the embedded Chromium instance.

EXPECTED RESULT
---------------
They should be.

SOFTWARE/OS VERSIONS
--------------------
> ```YAML
> Operating System: Fedora Linux 41
> KDE Plasma Version: 6.2.2
> KDE Frameworks Version: 6.7.0
> Qt Version: 6.8.0
> Kernel Version: 6.11.6-300.fc41.x86_64 (64-bit)
> Graphics Platform: Wayland
> Processors: 12 × AMD Ryzen 5 7600X 6-Core Processor
> Memory: 30.4 GiB of RAM
> Graphics Processor: AMD Radeon RX 5700
> Manufacturer: ASRock
> Product Name: X670E Taichi
> ```

ADDITIONAL INFORMATION
----------------------

I have filed a similar ticket for the *icons* upstream — at https://issues.chromium.org/issues/378121132#comment1. I didn't consider that to be worth reporting here.

This ticket differs to that, because the font fallbacks are an unfortunate consequence of backward compatibility which Google has no desire to remediate.
Comment 1 Roke Julian Lockhart Beedell 2024-11-09 15:31:22 UTC 
Created attachment 175680 [details]
Screenshot of the "Fonts" KCM.
Comment 2 Nate Graham 2024-11-13 18:55:39 UTC 
Yes, that's because it internally uses QtWebEngine which uses Chromium which doesn't respect these settings.
Comment 3 Roke Julian Lockhart Beedell 2024-11-13 19:18:44 UTC 
(In reply to Nate Graham from comment #2)

Thanks. I thought it embedded Chromium directly. Per https://forum.qt.io/post/437001, it seems like Qt can consume the system font is a platform-independent manner, so I'll take this upstream, to the QtWebEngine developers.
Comment 4 Roke Julian Lockhart Beedell 2024-11-13 19:21:05 UTC 
(In reply to Nate Graham from comment #2)

On this note, I wanted to file another issue for the same, but about the colour scheme. However, I'd like to know whether it would best be filed here, or, again, at Qt's Jira, instead. Specifically, the undermentioned CSS code:

```CSS
HTML { color-scheme: light dark !important; }
```

...should make the browser utilize the in-use `.colors` file. This works on Firefox (Gecko) but not the Web Browser. I presume that Qt at least understands colour schemes - so again, this is not the purview of KDE Frameworks specifically?
Comment 5 Nate Graham 2024-11-14 17:06:20 UTC 
Qt, yeah.
Comment 6 Roke Julian Lockhart Beedell 2024-12-03 15:54:33 UTC 
(In reply to Nate Graham from comment #5)
Thanks. Reported to https://bugreports.qt.io/browse/QTBUG-131844.