1977735 - Firefox UI becomes unresponsive after active tab use with “Custom Contrast” setting on Ubuntu

Status: UNCONFIRMED

(Core :: Widget: Gtk, defect)

Description

[Matias]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:140.0) Gecko/20100101 Firefox/140.0

Steps to reproduce:

1. Launch Firefox on Ubuntu 24.04 LTS (Snap version).
2. Go to: Settings > General > Language and Appearance > Colors.
3. Set the override option to "Always" and choose "Custom" colors.
4. Start browsing websites, open and close multiple tabs.
5. After a few minutes, try clicking:
   • The ‘X’ on tabs
   • The menu (hamburger icon)
   • The padlock or site info icon
   • The bookmarks star
   • The translate icon

Actual results:

After a few minutes of active browsing with tabs being opened and closed, the Firefox UI becomes unresponsive:

• The 'X' close buttons on tabs stop working.
• The menu icon and site-related icons do not respond to mouse clicks.
• Other parts of the UI remain functional (e.g., Ctrl+W still closes tabs).
• No extensions are installed; only the custom contrast setting is enabled.

Expected results:

All interface elements, including tab close buttons and site/menu icons, should remain responsive to mouse input regardless of the custom contrast setting or browsing activity duration.

Comment 1

[BugBot [:suhaib / :marco]]

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

[Matias]

Let me know if a reduced test case or MOZ_LOG output would help. Happy to assist with additional diagnostics if needed.

Comment 3

[Matias]

I have reviewed the issue and agree with the Bugbug bot’s suggestion. The bug is related to GTK widget handling in Firefox on Linux, so assigning it to Core::Widget: Gtk is appropriate.

Comment 4

[Thinker Li [:sinker]]

Please check bug 1955112. Is it what you run into?
Could you reproduce the issue with Firefox Nightly?

Comment 5

[Martin Stránský [:stransky] (ni? me)]

Note that 141.0 release may fix that, comes out on Tuesday.