Firefox stopped inhibiting screensaver on video playback

[Eugene San]

Update (02/2024):
With Firefox 122 on Ubuntu-Mate 23.10, screensaver/powermanager inhibition is completely broken even with Mozilla's .deb package.

After a fresh start of firefox, screen saver is blocked properly when playing video but after opening/un-suspending a few tabs with video, inhibition stops working.

I was unable to come up with reproducible scenario but after a few hours of browsing it usually stops working. Restarting firefox fixes the problem.

The bug first appeared around August and affects both .deb and snap packages.

Tested on Ubuntu-Mate 22.04.3, Xorg, both Pulseaudio and Pipewire (if that's relevant).
I don't see any relevant msgs in xsession-errors or system logs.

[Amin Bandali (bandali)]

Hello,

Are you able to reproduce this on Ubuntu Noble (24.04), and with the latest version of Firefox? If so, would you please also open a bug report upstream on Mozilla's tracker at https://bugzilla.mozilla.org ?

Also, would you please double-check the system logs and also dmesg for any potentially relevant errors, such as AppArmor DENIED lines?

[Eugene San (eugenesan)]

To fix the issue, I was forced to switch to KDE Plasma (on the same system).
KDE Plasma had no issues with Firefox on both 23.10 and 24.04.

I opened a bug with Mate and there is already a bug report on bugzilla.
Unfortunately, no solution was provided so for now Mate + Firefox is not a practical combination.

Regarding error msgs and relevant log entries, there are none.
The problem seems to be related to DBUS communication between Mate and Firefox.

[Amin Bandali (bandali)]

I see, thanks for the update. Would you please provide the bug number on Bugzilla so we could potentially link it to this one Launchpad for future reference?

[Eugene San (eugenesan)]

@bandali
I believe this bug report on bugzilla is related: https://bugzilla.mozilla.org/show_bug.cgi?id=1862159

[Amin Bandali (bandali)]

Thanks, I'll amend this bug's metadata accordingly.