2016109 - Browser Screenshot popup is displayed below RDM UI

Status: RESOLVED FIXED

(DevTools :: Responsive Design Mode, defect, P1)

Description

[Julian Descottes [:jdescottes]]

Attachment: image.png

STRs:

• open a tab
• enable RDM
• click on the browser's screenshot button

ER:
The popup to select the screenshot mode should be fully visible
AR:
The popup is partially hidden by RDM

Comment 1

[Julian Descottes [:jdescottes]]

Seems to also impact modal dialogs (alert, print etc...)

Comment 2

[Julian Descottes [:jdescottes]]

Note that with Bug 2013120, the behavior is different. With the patch, the dialogs are fully constrained in RDM's viewport.

(except for the screenshot popup which still seems displayed in the same way as today)

Comment 3

[Mr. Beedell, Roke Julian Lockhart (RJLB) [:RokeJulianLockhart]]

Attachment: A Screenshot Of A Comparison Between `147.0.3` And `149.0a1`

I don't observe this in:

Name        : firefox
Version     : 147.0.3
Release     : 1.fc43
Architecture: x86_64
Install Date: Wed 11 Feb 2026 02:43:05 GMT
Size        : 306510089
Signature   :
              RSA/SHA256, Mon 09 Feb 2026 15:27:37 GMT, Key ID 829b606631645531
Source RPM  : firefox-147.0.3-1.fc43.src.rpm
Build Date  : Fri 06 Feb 2026 13:24:10 GMT
Build Host  : buildhw-x86-03.rdu3.fedoraproject.org
Packager    : Fedora Project
Vendor      : Fedora Project

However, I do in:

Name        : firefox-nightly
Version     : 149.0a1
Release     : 20260210213212
Architecture: x86_64
Install Date: Wed 11 Feb 2026 02:43:03 GMT
Size        : 376981720
Signature   : (none)
Source RPM  : firefox-nightly-149.0a1-20260210213212.src.rpm
Build Date  : Tue 10 Feb 2026 23:25:16 GMT
Build Host  : 3875e4b9471e
Vendor      : Mozilla

Consequently, I'll modify the report version, although the OS and architectures might be better as “All”.

Comment 4

[Julian Descottes [:jdescottes]]

Consequently, I'll modify the report version, although the OS and architectures might be better as “All”.

Thanks for checking! Also checked 148 and the issue is not visible there.

Comment 5

[Mihai Boldan, Desktop QA [:mboldan]]

I managed to find the regression.
Last good: 2026-01-27
First bad: 2026-01-28
Pushlog: https://hg-edge.mozilla.org/integration/autoland/pushloghtml?fromchange=fe51e64122f47555434601c73e26c02038eb3077&tochange=b23b7f23fefec37b3cdfbb06d7d880ea72e8047f
Potential regressor: Bug 1997929

Comment 6

[Julian Descottes [:jdescottes]]

Thanks for the investigation!

I confirm this is a regression from Bug 1997929.

RDM toolbar has a z-index set at https://searchfox.org/firefox-main/rev/036b98bf5ed3e11e8ca16a178a9357675ae15e1b/devtools/client/responsive/responsive-browser.css#22,25,38

.browserContainer.responsive-mode > .rdm-toolbar {
...
  z-index: var(--browser-stack-z-index-rdm-toolbar);
...
}

Variable is set at https://searchfox.org/firefox-main/rev/036b98bf5ed3e11e8ca16a178a9357675ae15e1b/browser/themes/shared/browser-shared.css#89-92

/* z-indices that fight on the browser stack */
--browser-stack-z-index-devtools-splitter: 1;
--browser-stack-z-index-dialog-stack: 2;
--browser-stack-z-index-rdm-toolbar: 3;

But the screenshots popup has z-index 1

https://searchfox.org/firefox-main/rev/036b98bf5ed3e11e8ca16a178a9357675ae15e1b/browser/themes/shared/browser-shared.css#679-683

.screenshotsPagePanel {
  position: relative;
  max-height: 0;
  z-index: 1; /* Above the web content in this stack. */
}

Comment 7

[Julian Descottes [:jdescottes]]

Attachment: Bug 2016109 - Update screenshots panel z-index to be above RDM toolbar r=sfoster!,nchevobbe

Comment 8

[Sam Foster [:sfoster] (he/him)]

I gave this a priority/severity then realized it was in the devtools not screenshots component. Feel free to adjust as needed.

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/024902d0c348
https://hg.mozilla.org/integration/autoland/rev/573842877739
Update screenshots panel z-index to be above RDM toolbar r=sfoster,desktop-theme-reviewers

Comment 11

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/573842877739