Remove browser.display.use_system_colors pref

After bug 1898096, use_system_colors will not be exposed in UI and won't have any affect. It will need to be removed along with its telemetry probes.

I'm separating this task from bug 1898096 in case the changes there need to be reverted so we won't have to re-introduce a pref and telemetry probe.

I don't believe that this should occur. Currently, this is the sole feasible way for me to override web content with my OS's colouration. Firefox provides no alternative except manually injecting :root { color-scheme: light dark } into every webpage I visit, etcetera.

This isn't merely an accessibility preference, as discuss.kde.org/t/29444/15 corroborates: it also provides theming. Unless id=1888225 is reconsidered, all about: pages are now OS-colouration inadherent.

It is very uncommon in on the web today to encounter unstyled content.

Surely web pages is not just text files. However over half of the web pages I visit do not offer light and dark themes at the same time.

Now with the setting and **any **dark DE, CONTRAST SETTINGS > Automatic (Use system settings) will expose the user to bright webpages (not just white) and their eyes.
This does not go well aesthetically with dark window decorations either so it looks broken.
I'm speaking for Linux, could not test anything else.

The ability to change the default colors without high contrast mode does not offer a good experience.

It provided a perfect experience for me. Of course, banners of web pages did not often change colors but the rest did very well and felt like a home experience.
One was able to inject the DE's accent and theming colors into the web layout. Now the whole thing just turns grayish.
One was able to inject the DE's accent and theming colors which adapted with the wallpaper you use. Perfect consistent theming while browsing. Perfect integration into KDE Plasma. _Gone _ with the wind!

There are three color palettes to choose from in light of the preference
above they are:

1. WIDGET_COLORS: The OS's configured colors used by its theme.

This is not true for KDE Plasma 5 or 6! No colors do get into Firefox web backgroud or fonts anymore!

CONTRAST SETTINGS > Automatic (Use system settings) does not include KDE Plasma 5.27.12 or KDE Plasma 6.3.5 colors into web pages.
Neither does it consistently provide a dark theming without using third party add-ons like Dark Reader (which lets webpages blink up white before theming them dark for a fraction of a second as well).

PLEASE bring back the old setting:
Colors > Use System Colors | Always

I don't see any reason this was removed.
Bring it back into - Custom or:
Make it at least available in about:config as a fallback for users who don't want the Contrast Control setting if they use their browser theming (consistent with wallpaper and all web content!)

Cheers a disappointed KDE Plasma costumizing user!

(^ quotation incorrect in above post, please remove.)

It is very uncommon in on the web today to encounter unstyled content.

Surely web pages is not just text files. However over half of the web pages I visit do not offer light and dark themes at the same time.

Now with the setting and **any **dark DE, CONTRAST SETTINGS > Automatic (Use system settings) will expose the user to bright webpages (not just white) and their eyes.
This does not go well aesthetically with dark window decorations either so it looks broken.
I'm speaking for Linux, could not test anything else.

The ability to change the default colors without high contrast mode does not offer a good experience.
It provided a perfect experience for me. Of course, banners of web pages did not often change colors but the rest did very well and felt like a home experience.
One was able to inject the DE's accent and theming colors into the web layout. Now the whole thing just turns grayish.
One was able to inject the DE's accent and theming colors which adapted with the wallpaper you use. Perfect consistent theming while browsing. Perfect integration into KDE Plasma. _Gone _ with the wind!

There are three color palettes to choose from in light of the preference
above they are:

1. WIDGET_COLORS: The OS's configured colors used by its theme.

This is not true for KDE Plasma 5 or 6! No colors do get into Firefox web backgroud or fonts anymore!

CONTRAST SETTINGS > Automatic (Use system settings) does not include KDE Plasma 5.27.12 or KDE Plasma 6.3.5 colors into web pages.
Neither does it consistently provide a dark theming without using third party add-ons like Dark Reader (which lets webpages blink up white before theming them dark for a fraction of a second as well).

PLEASE bring back the old setting:
Colors > Use System Colors | Always

I don't see any reason this was removed.
Bring it back into - Custom or:
Make it at least available in about:config as a fallback for users who don't want the Contrast Control setting if they use their browser theming (consistent with wallpaper and all web content!)

Cheers a disappointed KDE Plasma costumizing user!

browser.display.use_system_colors
is still in about:config
But is not working the way it did before the Contrast Control UI settings were introduced!

WIDGET_COLORS: The OS's configured colors used by its theme.

This is not true for KDE Plasma 5 or 6! No colors do get into Firefox web backgroud or fonts anymore! "Contrast Settings" > "Automatic" (Use system settings) does not include KDE Plasma 5.27.12 or KDE Plasma 6.3.5 colors into web pages.

On that note, although I've no introspection into the browser source (I don't understand how to utilise Mercurial), the previous implementation adhered to the QPalette that KColorScheme exposes. Now, although it continues to adhere to Qt::ColorScheme (at least, as exposed by org.freedesktop.appearance's color-scheme), it always sets brand colours, instead of what the QPalette defines.

I really think that at least either this or id=1888225 need to be reconsidered, since although I can understand wanting to remove a non-CSS-based CSS override, I do not understand taking away the sole workaround for having the entire browser themed like the DE.

@Mr. Beedell, Roke Julian Lockhart (RJLB)
I'm debating whether or not to revert https://bugzilla.mozilla.org/show_bug.cgi?id=1898096 in my fork r3dfox. (and by extension https://bugzilla.mozilla.org/show_bug.cgi?id=1952693, and https://bugzilla.mozilla.org/show_bug.cgi?id=1952328) It seems to break a lot of stuff, and made the colors funny. However I also don't know if it is entirely worth it or if I would want to maintain the changes on the long term once things (i hope) eventually get smoothed out.
I'd also revert this if it comes to happen, and at least look into https://bugzilla.mozilla.org/show_bug.cgi?id=1888225

So I'm going to let you decide what I do.

(In reply to k4sum1 from comment #6)

So I'm going to let you decide what I do.

Thank you for looking into this! I'm honoured. Let's discuss this at Eclipse-Community/r3dfox/issues/30, since, fortunately or unfortunately, discussions here are generally for upstream, and I can't violate that and retain EDITBUGS! 😅

I'm a new contributor, and I'll be submitting a patch for this soon.

https://hg.mozilla.org/mozilla-central/rev/34343931ea62

https://hg.mozilla.org/mozilla-central/rev/34343931ea62