1773795 - Firefox uses a different 'windowtext' color differs from Chrome (making e.g. MS OneDrive Word docs appear darker/easier-to-read in Chrome)

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[Daniel Holbert [:dholbert]]

STR:

1. Load attached testcase.
2. Click the text and see what the alert says.

ACTUAL RESULTS:
Firefox reports rgb(61, 61, 61) i.e. a grayish color.

EXPECTED RESULTS:
Chrome reports rgb(0, 0, 0) i.e. black.

I suspect that strictly speaking this is a UA-defined color and we use whatever color we deem appropriate (or maybe we get it from the OS? Though I'd expect that Firefox and Chrome would get the same color in that case...)

This causes Firefox to look noticeably "fainter" than Chromium-based browsers on OneDrive's Word Document Editor (which seems to use color: windowtext by default).

Screenshot with Firefox on the left, Chrome on the right:
https://bugzilla.mozilla.org/attachment.cgi?id=9280762

(I originally posted this on bug 1773699 but then realized that I was seeing a different issue than the reporter; hence, I'm spinning this bug here off for the issue that I'm seeing.)

I'm using Ubuntu 22.04, FWIW.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: testcase 1

Comment 2

[Daniel Holbert [:dholbert]]

FWIW in Firefox on Windows 10 (which I just tested via BrowserStack), it looks like we do indeed use rgb(0,0,0) -- i.e. I get "expected results" there.

But in Firefox Nightly on MacOS, I get rgba(0, 0, 0, 0.847) -- i.e. partially-transparent black. I imagine this color (much like the opaque gray color that I'm getting on Ubuntu) is harder-to-see than regular black on MS Word documents viewed in OneDrive...

emilio, do you know offhand where this windowtext system-color value comes from?

Comment 3

[Andrés Segarra]

I am the one who reported the original bug. Your test case reports windowtext as rgb(46, 52, 54). I'm in Fedora linux 36 KDE

Comment 4

[Emilio Cobos Álvarez (:emilio)]

WindowText comes from the OS theme here.

Comment 5

[Emilio Cobos Álvarez (:emilio)]

They are using the window / windowtext color correctly at least. We could make them match the Windows colors, but I'm not sure it's worth it.

Comment 6

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1773795 - Spoof window/windowtext colors in content. r=dholbert

Comment 7

[Emilio Cobos Álvarez (:emilio)]

So I'm not sure comment 6 is a great idea, but it should help for this specific case.

Comment 8

[Andrés Segarra]

could we do a specific page fix? Spoof window color only in Microsoft Office?

Comment 9

[Emilio Cobos Álvarez (:emilio)]

We could, but adding site-specific hacks is not a great use of time IMO. We could try to ping Microsoft folks to see if they can fix their page.

Also, I guess the spec says that Window/WindowText should be just Canvas/CanvasText, which this patch would achieve: https://drafts.csswg.org/css-color-4/#window

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/26d5615493b5
Spoof window/windowtext colors in content. r=dholbert

Comment 11

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/26d5615493b5