I was able to reproduce this with Firefox on Ubuntu 22.04, but not on 24.04, for what it's worth.
Would you please also report this issue on upstream's tracker https://bugzilla.mozilla.org ? (Even though this may have to do with one of the underlying system packages beneath Firefox/Thunderbird.) ** Changed in: firefox (Ubuntu) Status: New => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2065382 Title: Screen flashing when hoovering over menus To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/2065382/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
