1773155 - Firefox preferences' in-content-dialogs turn blank white, when you hover them with inspector element-picker, in dark mode

Status: VERIFIED FIXED

(Core :: Layout, defect)

Description

[Daniel Holbert [:dholbert]]

STR:

1. Make Firefox use dark mode for content (in about:preferences, you want Website appearance: dark)
2. Open some in-content "dialog" in Firefox Preferences -- e.g. in Preferences' search field, type and click the button for "Advanced" (font preferences) or "Manage Colors" or "Manage Exceptions".
3. Open DevTools (F12)
4. Click DevTools' element-picker button (at top left)
5. Hover over the dialog that you opened in step 2.

ACTUAL RESULTS:
The whole dialog turns blank white; the content can't be seen.
(though you can still sort-of see that it's there via the element-picker overlay. Dropdown menus still successfully open, too, if you manage to click the correct spot.)

EXPECTED RESULTS:
No such change in appearance when hovered with element-picker.

mozregression tells me this was regressed by bug 1738380:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=0d8f25c4388af0894425506e71024044f4d3402a&tochange=f0c4c97a8e6aa34214f287cb499321b6a0186c2f

...which is not too surprising, since it looks like that bug had several other similar regressions (though I think all of the other ones have been fixed, but this one persists in latest Nightly 103.0a1 (2022-06-07))

Tentatively classifying as S2 on the assumption that this might similarly affect some category of web content. (Though if it turns out to be really limited to Firefox-internal-pages-being-inspected-by-devtools, then maybe it's not quite S2.)

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: screencast

Here's a screencast showing the bug. (It didn't seem to capture my cursor, so you'll have to use a little imagination and refer to the STR.)

Comment 2

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

Set release status flags based on info from the regressing bug 1738380

Comment 3

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1773155 - Ensure highlighter iframe for parent process is transparent. r=nchevobbe,jdescottes

By ensuring that it has color-scheme: light in both the embedder and the
embedded page.

Usually only the outer styling is necessary, but we generally assume
that chrome pages follow the OS color-scheme, so we need to make sure
both are set as light.

This might be able to go away depending on the resolution of
https://github.com/mozilla/wg-decisions/issues/774

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/fdbc7a65f87d
Ensure highlighter iframe for parent process is transparent. r=nchevobbe

Comment 5

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/fdbc7a65f87d

Comment 6

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

The patch landed in nightly and beta is affected.
:emilio, is this bug important enough to require an uplift?
If not please set status_beta to wontfix.

For more information, please visit auto_nag documentation.

Comment 7

[Emilio Cobos Álvarez (:emilio)]

Comment on attachment 9280154 [details]
Bug 1773155 - Ensure highlighter iframe for parent process is transparent. r=nchevobbe,jdescottes

Beta/Release Uplift Approval Request

• User impact if declined: This affects mostly the inspector in privileged pages, but it's a simple enough fix that might be worth uplifting.
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: comment 0
• List of other uplifts needed: none
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Pretty simple / well-understood fix
• String changes made/needed: none
• Is Android affected?: No

Comment 8

[Pascal Chevrel:pascalc (PTO until April 26)]

Comment on attachment 9280154 [details]
Bug 1773155 - Ensure highlighter iframe for parent process is transparent. r=nchevobbe,jdescottes

Approved for 102 beta 6, thanks.

Comment 9

[Pascal Chevrel:pascalc (PTO until April 26)]

https://hg.mozilla.org/releases/mozilla-beta/rev/dba153afe5cb

Comment 10

[Giorgia Nichita, Release Desktop QA]

Reproduced this issue on an affected nightly build from 2022-06-07, on Windows 10 x64.
Verified as fixed on Firefox 102.0b7 (20220612185901) and 103.0a1 (20220614082301) on Win 10, macOS 10.14 and Ubuntu 21.04.