(copied from Arch Linux bug https://bugs.archlinux.org/task/26702?project=1&string=gnome-shell-extension-alternate-tab )

Description: Pressing alt+tab doesn't change doesn't switch focus to the next window, window selection interface is not shown and screen remains unusable until ESC is pressed (can not use/move any of open application windows)


Additional info:
* package version(s)
gnome-shell 3.2.1-1
gnome-shell-extension-alternate-tab 3.2.1-0.20111018 

* .xsession-errors when pressing alt+tab. Last line is shown after pressing ESC.
<code>
JS ERROR: !!! Exception was: TypeError: otherApps is undefined
JS ERROR: !!! lineNumber = '899'
JS ERROR: !!! fileName = '"/usr/share/gnome-shell/js/ui/altTab.js"'
JS ERROR: !!! stack = '"([object Array])@/usr/share/gnome-shell/js/ui/altTab.js:899
([object Array])@/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js:489
WindowList([object Array])@/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js:482
()@/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js:403
()@/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js:350
AltTabPopup2()@/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js:323
("switch_windows",null)@/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js:37
doAltTab([object _private_Shell_WM],"switch_windows",8,null,false)@/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js:556
"'
JS ERROR: !!! message = '"otherApps is undefined"'
JS ERROR: !!! Exception was: TypeError: this._appIcons is undefined
JS ERROR: !!! lineNumber = '475'
JS ERROR: !!! fileName = '"/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js"'
JS ERROR: !!! stack = '"()@/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js:475
([object _private_Shell_GenericContainer],[object _private_Clutter_Event])@/usr/share/gnome-shell/js/ui/altTab.js:305
"'
JS ERROR: !!! message = '"this._appIcons is undefined"'
JS ERROR: !!! Exception was: TypeError: this._appIcons is undefined
JS ERROR: !!! lineNumber = '475'
JS ERROR: !!! fileName = '"/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js"'
JS ERROR: !!! stack = '"()@/usr/share/gnome-shell/extensions/alternate-tab@gnome-shell-extensions.gnome.org/extension.js:475
([object _private_Shell_GenericContainer],[object _private_Clutter_Event])@/usr/share/gnome-shell/js/ui/altTab.js:305
"'
JS ERROR: !!! message = '"this._appIcons is undefined"'
Window manager error: Log level 8: g_source_remove: assertion `tag > 0' failed
</code>

Steps to reproduce:
1. Enable Gnome Shell Alternate Tab extension
2. Press alt+tab