** Summary changed: - screen or window starts flickering and won't stop [visual bell a11y] + visual bell (a11y) induced permanent flickering
** Description changed: A few times I have observed that my gnome-terminal starts flickering. The flickering part depends on the original size of the window, so if I enlarge the terminal, the flickering parts stay on the left. (See video below.) The entire terminal is affected. Switching between tabs changes nothing. Other gnome-terminal windows are unaffected. Closing all tabs makes the problem go away. + + [ Update: 2026-05-04 ] + + And, because I suspected the visual bell at play. I switched flash area + from "Entire Window" to "Entire Screen". And lo and behold, after the + weekend I found my entire "locked screen" in flicker mode. After logging + in, the same flicker was observed. Added to video below. ## Prior bugs This reminds me a lot of this bug: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2064716 There, the visual bell (a single flicker) during screensaver caused the terminal to stay dark. There the placement of the wrong/dark bits also depended on the original size. See this image https://launchpadlibrarian.net/727414302/gnome-terminal-very-dark-on- the-right.png (the right terminal is dark, while the left one is untouched). That bug was fixed by: https://gitlab.gnome.org/GNOME/mutter/-/commit/906920cb333486fd9ecd553cc819e2cd9799da6c ## This bug - The bug looks like this: + The [entire window] bug looks like this: === !EPILEPSY WARNING! === - https://junk.devs.nu/2026/bug-flickering-terminal/flickering-terminal-window-20260428-noble.webm + https://junk.devs.nu/2026/lp2150570-flickering-visual-bell-bug/flickering-terminal-window-20260428-noble.webm + === !EPILEPSY WARNING! === + + The entire screen bug looks like this (added 2026-05-04): + === !EPILEPSY WARNING! === + https://junk.devs.nu/2026/lp2150570-flickering-visual-bell-bug/flickering-entire-screen-20260504-noble.webm === !EPILEPSY WARNING! === It has only happened to me 3 or 4 times now, since this Ubuntu/Noble install. And I don't know how to reproduce it. I'm running X11. It has happened both with libmutter 46.2-1ubuntu0.24.04.15 (which contains the fix I mentioned) and the version I had before that (probably 46.2-1ubuntu0.24.04.14). - I don't know which component is to blame, so this might again not be a - gnome-terminal issue, but e.g. libmutter or gnome-shell. + I don't know which component is to blame [maybe] libmutter or gnome- + shell. Current versions: - linux 6.17.0-20-generic - gnome-shell 46.0-0ubuntu6~24.04.13 - gnome-terminal 3.52.0-1ubuntu2 - libmutter-14-0:amd64 46.2-1ubuntu0.24.04.15 I didn't find anything suspicious in journald (--user or root). I did see a bunch of these: GLIB_DOMAIN=Clutter MESSAGE=Can't update stage views actor unnamed [MetaSurfaceActorX11] is on because it needs an allocation. But they appear both before and after the bug. - I would not be surprised if the Visual Bell (Flash Area set to "Entire - window") was to blame again. + I would not be surprised if the Visual Bell was to blame again. Let me know if I can get you any other info. Cheers, Walter Doekes OSSO B.V. ( Cross-posted-to: - https://gitlab.gnome.org/GNOME/mutter/-/work_items/4776 ) + https://gitlab.gnome.org/GNOME/mutter/-/work_items/4776 -- which is + closed because Noble libmutter is older than 49. ) -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gnome-terminal in Ubuntu. https://bugs.launchpad.net/bugs/2150570 Title: visual bell (a11y) induced permanent flickering To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/2150570/+subscriptions -- desktop-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
