1852176 - Only Windows system fonts recognized in Private browsing

Status: RESOLVED INVALID

(Core :: Layout: Text and Fonts, defect)

Description

[delvier4]

Attachment: Left: Normal browsing, Right: Private browsing. Browser-wide sans-serif font is set to Arial Nova.

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/119.0

Steps to reproduce:

Browsing in Private mode

Actual results:

In Private browsing, everything is rendered only with Windows system fonts. Firefox's browser-wide font settings and CSS font-family properties are all ignored.

Expected results:

The expected look should have no differences between in normal browsing and Private browsing.

Comment 1

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

The Bugbug bot thinks this bug should belong to the 'Core::Layout: Text and Fonts' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Masatoshi Kimura [:emk]]

This is intentional change by bug 1826408. You can set the layout.css.font-visibility.private pref value to 3 to restore the old behavior.

Comment 3

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

:timhuang, since you are the author of the regressor, bug 1826408, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 4

[delvier4]

(In reply to Masatoshi Kimura [:emk] from comment #2)

This is intentional change by bug 1826408. You can set the layout.css.font-visibility.private pref value to 3 to restore the old behavior.

So that was intended. Thank you for informing me in advance.

Comment 5

[Daniel Holbert [:dholbert]]

Sounds like we can close this then. (Closing as "invalid" since the reported outcome is in fact the intended behavior, based on a change to the default value of an about:config pref.)

Comment 6

[Daniel Holbert [:dholbert]]

Side note: it is quite unfortunate that Windows doesn't have any font available for the characters in question here.

For future reference:

• The page shown in the screenshot is https://wikisource.org/wiki/Kaesong_mirror_inscription
• The text is styled with font-family: "Noto Fangsong KSS Rotated","Khitan Small Rotated";
• The first missing UTF character there is https://util.unicode.org/UnicodeJsps/character.jsp?a=18C2D ("Khitan Small Script Character-18C3A")

Comment 7

[Daniel Holbert [:dholbert]]

(In reply to Masatoshi Kimura [:emk] from comment #2)

This is intentional change by bug 1826408. You can set the layout.css.font-visibility.private pref value to 3 to restore the old behavior.

Correction: I think this preference (layout.css.font-visibility.private) was removed in bug 1847599, specifically here:
https://hg.mozilla.org/mozilla-central/rev/eb06ef97c8af#l2.28

So I suspect the most-direct way to get back the old behavior here is to change privacy.fingerprintingProtection.pbmode to false (which is the preference that bug 1849903 enabled beyond Nightly in version 118). [EDIT: see the end of bug 1852239 comment 3 for the recommended pref/value to use to restore the old behavior.]

Comment 8

[Jonathan Kew [:jfkthame]]

(In reply to Daniel Holbert [:dholbert] from comment #6)

Side note: it is quite unfortunate that Windows doesn't have any font available for the characters in question here.

For future reference:

• The page shown in the screenshot is https://wikisource.org/wiki/Kaesong_mirror_inscription
• The text is styled with font-family: "Noto Fangsong KSS Rotated","Khitan Small Rotated";
• The first missing UTF character there is https://util.unicode.org/UnicodeJsps/character.jsp?a=18C2D ("Khitan Small Script Character-18C3A")

It's unfortunate Windows doesn't have support yet, but the Khitan Small Script block was only added to Unicode in v13.0, so it's a relatively recent addition. Presumably a future Windows version will eventually include font coverage.

(FWIW, my macOS 13.4 system doesn't have font support for this either.)

Comment 9

[Daniel Holbert [:dholbert]]

(In reply to Jonathan Kew [:jfkthame] from comment #8)

(FWIW, my macOS 13.4 system doesn't have font support for this either.)

(My Ubuntu 22.04 system doesn't render the characters on https://wikisource.org/wiki/Kaesong_mirror_inscription either.)

(In reply to Daniel Holbert [:dholbert] from comment #7)

(In reply to Masatoshi Kimura [:emk] from comment #2)
Correction: I think this preference (layout.css.font-visibility.private) was removed in bug 1847599, specifically here:
https://hg.mozilla.org/mozilla-central/rev/eb06ef97c8af#l2.28

So I suspect the most-direct way to get back the old behavior here is to change privacy.fingerprintingProtection.pbmode to false

Update: no need to toggle that pbmode pref -- Tom describes a more targeted way to get back the old behavior at the end of bug 1852239 comment 3, using a custom value for privacy.fingerprintingProtection.overrides.