gala crashed with SIGSEGV in meta_window_appears_focused()

StacktraceTop:
 meta_window_appears_focused () from /tmp/tmprvdf_C/usr/lib/libmutter.so.0
 ?? () from /tmp/tmprvdf_C/usr/lib/libmutter.so.0
 _clutter_actor_get_paint_volume_real (pv=0x9852534, self=0x9852368) at ./clutter-actor.c:15420
 _clutter_actor_get_paint_volume_mutable (self=0x9852368) at ./clutter-actor.c:15496
 clutter_clone_get_paint_volume (actor=0x98df3f0, volume=0x98df5bc) at ./clutter-clone.c:213

@dan: please don't mark bugs as critical without an explanation. medium is fine for a crash happening to one person.

this is suppose to be fixed in trunk rev 245

Still happens as of trunk rev 264, see bug 1083657

See bug 1032800, possible duplicate? It's been suggested that the crash occurs when gala tries to switch to a non-existent window.

Gala crashed while I was activating "expose windows" in a corner and applications menu in an other corner in the next second... Sometimes that puts the app menu window with the others in "exposé mode" sometimes it switches from "exposé" to normal view with app menu open...

From another bug: "I have this bug using the following steps

Assign the following hot corners:

Top left: Open Luncher
Bottom left: Show workspace view
Bottom right: Expose all windows

And then, play with it by moving the mouse to:
"bottom left",
"bottom right", (without quitting the workspace view)
"bottom right",
"bottom right",
"bottom left",
"bottom right",
"top left",
"top left"

I'm not sure it's the shortest path, but it always crashes on my computer using the following procedure."

Hello, everybody.

It's happening to me as well.
I have set the hot corners but almost all the times when this crash happens these are the conditions:

I let the PC idle for a while with a lot of apps open (I'm using it to work, so usually I have open Firefox, Aptana, Filezilla, files explorer, Thunderbird, GIMP, Fireworks (with Wine), etc....), then when I return to work I try to Super+A to expose all windows or just press Alt+Tab to switch between them and all freezes... then Gala crashes....

I have a low level notebook with 2 G of RAM.

Bumping importance because of sheer number of duplicate bugs and people affected.

I've had the same problem, I've set the bottom right corner as a hotspot to activate the workspace overview. I have two Google chrome windows open and I switch to a new workspace. I right click on the chrome icon in Docky and click on one of the two chrome windows that I have running in the hope that just that chrome window will move to the new workspace instead gala crashes. I've tried this twice and the same thing has happened both times.

I tracked down two sources of this crash, one when exposing all windows and a window closes, that is not on the current workspace and a second one, when a window closes while alt-tabbing. Those are fixed now. I hope those were the only places causing this bug, if we get another report of it, we'd have to reopen it.

I had the problem several times (but not always) with the following workflow:
Browse photos in fullscreen mode in Gwenview > right-click > Open with GIMP > Alt+Tab because widow doesn't show up > crash

Happens every time running Netbeans, Google Chrome and a Terminal Window for debugging, i'm a web app developer so this gets anoying. thanks.

@axzelmarin, every time as in you can easily reproduce the crash? If so, some exact steps to make it crash or even better a screencast of the crash happening would be awesome!

Tom Beckmann, if i run Filezilla and tell it to watch files for changes, then alt-tab back from editing that file, sometimes (maybe 20% of the time) the upload dialog will be treated like a separate window. Then when i alt-tab again it is not (so it is focused) and confirm it (which closes it), as soon as i alt-tab away from Filezilla, Gala crashes with this message.

@lewis, do you think you can get that on a screencast? I had trouble reproducing it.

Hi. This bug has been annoying me for months. I'm glad I found a bug report on it.

As with other contributors to this report, very often when I switch windows with Alt+Tab gala crashes, leaving me without window compositing. But I usually have no crash report to submit because apport does not intercept the crash.
Hopefully, this morning when the crash happened I opened a terminal and relaunched gala. A few minutes later, it crashed again, leaving me this log :

:~$ gala
Avertissement du gestionnaire de fenêtres : Log level 128: Preferences.vala:328: Loading preferences from file '/home/XXX/.config/plank/dock1/settings'
Avertissement du gestionnaire de fenêtres : Log level 16: Preferences.vala:184: '/usr/share/plank/themes/Pantheon/dock.theme' is read-only!
Avertissement du gestionnaire de fenêtres : Log level 128: Preferences.vala:328: Loading preferences from file '/usr/share/plank/themes/Pantheon/dock.theme'
Avertissement du gestionnaire de fenêtres : Log level 128: Settings.vala:158: Loading settings from schema 'org.pantheon.desktop.gala.keybindings'
Avertissement du gestionnaire de fenêtres : Log level 128: Settings.vala:158: Loading settings from schema 'org.pantheon.desktop.gala.shadows'
Avertissement du gestionnaire de fenêt res : Log level 128: Settings.vala:158: Loading settings from schema 'org.pantheon.desktop.gala.behavior'
Avertissement du gestionnaire de fenêtres : Log level 8: gtk_style_context_add_provider: assertion `GTK_IS_STYLE_PROVIDER (provider)' failed
Avertissement du gestionnaire de fenêtres : Log level 128: Settings.vala:158: Loading settings from schema 'org.pantheon.desktop.gala.animations'
Avertissement du gestionnaire de fenêtres : Log level 8: meta_frames_get_borders: assertion `type < META_FRAME_TYPE_LAST' failed
Avertissement du gestionnaire de fenêtres : meta_window_activate called by a pager with a 0 timestamp; the pager needs to be fixed.
Avertissement du gestionnaire de fenêtres : Log level 16: STACK_OP_LOWER_BELOW: sibling window 0x4800001 not in stack
Avertissement du gestionnaire de fenêtres : Log level 16: WindowSwitcher.vala:384: No clone found for removed window
Avertissement du gestionnaire de fenêtres : Log level 16: WindowSwitcher.vala:384: No clone found for removed window
Erreur de segmentation

(N.B. : french for Segmentation Fault, obviously)

Second crash in two days in a row. Same as the others, but I have to precise I use 2 screens (the one integrated to my laptop, and an external screen).

RAM/proc limitations are not the cause of this problem (16GB RAM with i7-4500 CPU). The bug happens when the laptop is idle for some time (like one hour, lunch break...). I get back to work, and... kaboom.
Each time this bug happened, I was using Thunderbird + Chromium-browser + Terminal + VLC + Pidgin.

Hope this might help, and please ask if more details are needed :)