1720508 - Ability to override prefers-color-scheme for web pages only

Status: RESOLVED DUPLICATE of bug 1707872

(Core :: Widget: Gtk, defect)

Description

[Vincent Bernat]

Attachment: 2021-07-14_17-57.png

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:90.0) Gecko/20100101 Firefox/90.0

Steps to reproduce:

On Linux:

1. Use a GTK dark theme.
2. Use "Dark" as Firefox theme
3. Set ui.systemUsesDarkTheme to 0

Actual results:

1. Web pages are not using the dark theme (good)
2. Firefox interface mixes light and dark theme (not good)

Popup menus are white. Save dialog box is using a light theme, but some items are rendered as dark.

Expected results:

1. Web pages are not using the dark theme
2. Firefox is using the dark theme

I realize that I am lying by setting ui.systemUseDarkTheme to 0. Up to Firefox 89, this was providing the expected result. I want to use a dark interface but I want the pages to be rendered as "light". Alternatively, there should be a dedicated setting to set prefers-color-scheme for web sites.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Firefox::Theme' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Comment 2

[Vincent Bernat]

This is definitely not the right approach, but using this patch, I get what I want: dark theme for interface, light theme for web pages. I can put a new preference settings for that if it would be accepted.

--- firefox-90.0.orig/dom/base/Document.cpp
+++ firefox-90.0/dom/base/Document.cpp
@@ -17160,7 +17160,7 @@ StylePrefersColorScheme Document::Prefer

   const bool dark =
       !!LookAndFeel::GetInt(LookAndFeel::IntID::SystemUsesDarkTheme, 0);
-  return dark ? StylePrefersColorScheme::Dark : StylePrefersColorScheme::Light;
+  return StylePrefersColorScheme::Light;
 }

 // static

Also, see 1547818. I'd rather prefer a preference in about:config, but I would also accept a web extension.

Comment 3

[Petruta Horea [:phorea], Desktop QA]

I could reproduce the issue in Firefox 90 under Ubuntu 18.04 64-bit.
However, this is already fixed in Firefox 91 beta 2 and latest Nightly 92.0a1.
Can you please give it a try? Thank you!

Comment 4

[Vincent Bernat]

Hey!

Yes, it works just fine in Firefox 91 beta 2.

Thanks!

Comment 5

[Petruta Horea [:phorea], Desktop QA]

I checked with mozregression and found out that this bug was regressed by bug 1707957 in 90 and fixed by bug 1707872 in 91 (which will most probably ride the trains).