Comment 74 for bug 1181666

> On that note, everyone please UNLOAD ALL YOUR EXTENSIONS and verify this bug still happens without any. If you then find it was caused by a particular extension, please list it here.

It seems to be caused by the windows-alt-tab extension here.

I've been able to reproduce it if I have more than one application open, and press the META (Win key) + backtick shortcut that is normally bound to switch application window - but only if I have the windows-alt-tab extension loaded.

The following error shows up in syslog when pressing the key combination and the extension is loaded:

Oct 24 09:18:12 sxps gnome-shell[1888]: JS WARNING: [/<email address hidden>/extension.js 42]: reference to undefined property "actor"
Oct 24 09:18:12 sxps gnome-shell[1888]: JS ERROR: TypeError: actor is undefined#012pushModal@resource:///org/gnome/shell/ui/main.js:436:9#012AltTabPopupW<.show@/home/stian/.local/share/gnome-shell/extensi
<email address hidden>/extension.js:42:14#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012doAltTab@/<email address hidden>/exten
sion.js:443:5

The workaround if I accidentally press the combination is logging out and logging in again.