1754592 - With HCM enabled and Firefox's default theme, primary buttons' focus rings are invisible

Status: VERIFIED FIXED

(Toolkit :: Themes, defect)

Description

[Itiel]

(The above title is a manifestation of the actual issue; feel free to rename as you see fit)

STR:

1. Set Windows to White HCM, non dark mode
2. Set Nightly to default theme
3. Open any webpage
4. Open the bookmarks panel and tab to Save (or even the checked checkbox before it), you'll see no focus ring as it's set to white -- the same as the "Save" text color

AR:
The focus ring blends with the doorhanger white background

ER:
Visible focus ring

Comment 1

[Itiel]

This regressed by bug 1706534 but it's not "to blame", as it seems the "nested" vars (--focus-outline is made of more vars, including --focus-outline-color) this patch uses, cause the outline color to fallback to currentColor.
The CSS responsible here is at:
https://searchfox.org/mozilla-central/source/toolkit/themes/shared/popupnotification.inc.css#146-149,162

Quoting morgan from Matrix, a11y channel:

I think I figured it out -- --focus-outline-color decomposes to outline: 2px <vars>. outline gets further decomposed into outline-[style|color|width]. We ignore outline-colors when processing our style sheet in forced colors mode: https://searchfox.org/mozilla-central/rev/c12a59323ee46b29b90c9917a3a7a70ea714ffec/servo/components/style/properties/longhands/outline.mako.rs#20

its initial color is currentColor, which is what gets rendered when we revert

Comment 2

[Emilio Cobos Álvarez (:emilio)]

Per discussion the outline color should be -moz-accent-color, which should work because it's a system color. Works here on Linux with high-contrast white, but I might be missing something. I can test Windows tomorrow I guess.

Comment 3

[Emilio Cobos Álvarez (:emilio)]

Wait but this is in the parent process, so I'm clearly missing something, because we don't do those restrictions there.

Comment 4

[Emilio Cobos Álvarez (:emilio)]

This is not a layout / CSS engine issue. See incoming test-case:

Comment 5

[Emilio Cobos Álvarez (:emilio)]

Attachment: Reduced test-case.

Comment 6

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

Set release status flags based on info from the regressing bug 1706534

Comment 7

[Giorgia Nichita, Release Desktop QA]

Reproduced this issue on an affected nightly build (2022-02-09) on Windows 10 x64.
Verified as fixed on Firefox 99.0b7 (20220322185926) on Windows 10 x64.