1984638 - [Ubuntu] Permission Panel UI glitch when showing/hiding camera preview

Status: NEW

(Core :: Widget: Gtk, defect)

Description

[Bianca Hidecuti, Desktop Test Engineering [:bhidecuti]]

Attachment: Screencast from 22.08.2025 10_19_25.webm

Found in

• 143.0b2

Affected versions

• 144.0a1
• 143.0b2

Tested platforms

• Affected platforms: Ubuntu 22.04 (x11)
• Unaffected platforms: macOS 13, Windows 11

Steps to reproduce

1. Go to https://mozilla.github.io/webrtc-landing/gum_test.html
2. Click on the "Camera" button
3. Click on the " Show preview" button from the permission panel and observe the behavior
4. Click on the "Hide preview" button from the permission panel and observe the behavior

Expected result

• No UI issues should be observed on the permission panel when showing/hiding the preview

Actual result

• When clicking the "Show preview" button, the preview is inserted with an extra offset, creating a duplicate-looking top section. This misplacement causes the preview to overlap the "Hide preview"
• When clicking the "Hide preview" button, the top section of the panel is duplicated and the preview is not hidden smoothly

Regression range

• Not a regression as this is reproducing since enhancement 799415 was implemented

Additional notes

• The issue is resolved after hovering the permission panel
• Not reproducing on Windows and macOS

Comment 1

[Emma Zühlcke [:emz]]

I can't reproduce on my Ubuntu VM running wayland. I wonder if the rendering glitches are related to x11?

Comment 2

[Bianca Hidecuti, Desktop Test Engineering [:bhidecuti]]

(In reply to Emma Zühlcke [:emz] from comment #1)

I can't reproduce on my Ubuntu VM running wayland. I wonder if the rendering glitches are related to x11?

Hi!
I can also confirm that the issue does not occur on Wayland and only occurs on X11.

Comment 3

[Thinker Li [:sinker]]

Could you try mozregression to identify the range of regression?

Comment 4

[Bianca Hidecuti, Desktop Test Engineering [:bhidecuti]]

(In reply to Thinker Li [:sinker] from comment #3)

Could you try mozregression to identify the range of regression?

Hi. This has been reproducible since the camera preview was introduced in the permission panel as part of bug 799415.