2032057 - black borders on menus and elements

Status: ASSIGNED

(Toolkit :: Themes, defect)

Description

[zlice]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:151.0) Gecko/20100101 Firefox/151.0

Steps to reproduce:

update nightly the other day

Actual results:

some gtk borders are not composited by firefox in x11. black borders appear.

file menu - fine
hamburger menu - black borders
add bookmark - black border

Expected results:

transparency composited firefox side

Comment 1

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

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

Comment 2

[zlice]

2026-05-17T09:27:30.819000: DEBUG : Found commit message:
Bug 2019097 - Rename `--arrowpanel-*` variables to `--panel-*`, consolidate with `--panel-*` variables in `popup.css` r=desktop-theme-reviewers,tabbrowser-reviewers,places-reviewers,omc-reviewers,urlbar-reviewers,Standard8,aminomancer,sthompson,dao,devtools-reviewers,nchevobbe

Differential Revision: https://phabricator.services.mozilla.com/D285906


2026-05-17T09:27:30.819000: DEBUG : Did not find a branch, checking all integration branches
2026-05-17T09:27:30.820000: INFO : The bisection is done.
2026-05-17T09:27:30.820000: INFO : Stopped

Comment 3

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

:oarnesto, since you are the author of the regressor, bug 2019097, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 4

[Thinker Li [:sinker]]

Could you provide a screenshot and share about:support?

Comment 5

[zlice]

Attachment: about-support.txt

screenshots immediate close the pop-up windows like add-bookmark or the hamburger menu. it's a black square with the rounded-edge menu inside

Comment 6

[Thinker Li [:sinker]]

Could you record a short video instead?

Comment 7

[zlice]

Attachment: bookmarksblackborder.mp4

had to do desktop and crop for it to show up. hope that helps.

Comment 8

[serious7046]

Confirming this issue on Firefox 151.0 stable (not just Nightly).
Environment: Fluxbox WM, X11, no compositor running.
Workaround: Starting xcompmgr -C fixes the black borders.
Also fixed (Qwen3.6-Plus) by userChrome.css override of --panel-border-radius and --panel-shadow-margin.

1. about:config
   toolkit.legacyUserProfileCustomizations.stylesheets=true

2. ~/.mozilla/firefox/[NAME_PROFILE]/chrome/userChrome.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

panel, menupopup, #appMenu-popup, .panel-arrowcontent {
--panel-shadow-margin: 0px !important;
--arrowpanel-shadow-margin: 0px !important;
--panel-border-radius: 0 !important;
--arrowpanel-border-radius: 0 !important;
box-shadow: none !important;
border: none !important;
}
.panel-arrow { display: none !important; }

Comment 9

[Thinker Li [:sinker]]

Hi Dao, this bug seems to be an issue of media features.
Could you take a look?

Comment 10

[Nathan]

I just updated Firefox to 151.0.1 stable and can confirm that I now have this issue (running in Bodhi Linux Standard Edition, an Ubuntu derivative).

Comment 11

[klk745]

Same problem here with 151.0.1 on Linux Mint Xfce 22.3 (X11).

Comment 14

[Dão Gottwald [:dao]]

Attachment: Bug 2032057 - Make sure we override --panel-box-shadow-margin and --panel-border-radius for arrow panels when Gtk CSD transparency is unavailable. r?oarnesto

Comment 15

[Dão Gottwald [:dao]]

(In reply to Thinker Li [:sinker] from comment #9)

Hi Dao, this bug seems to be an issue of media features.
Could you take a look?

Yeah, thanks; this is a front-end issue caused by bug 2019097. The media features resolve correctly, we weren't just using them correctly.

Comment 16

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/9e08b88fa218
https://hg.mozilla.org/integration/autoland/rev/db0386f497e3
Make sure we override --panel-box-shadow-margin and --panel-border-radius for arrow panels when Gtk CSD transparency is unavailable. r=desktop-theme-reviewers,emilio

Comment 17

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

Set release status flags based on info from the regressing bug 2019097