Hm, for me it's not intermittent at all. It happens as soon as I've sent a single message using Thunderbird; Gnome Shell simply becomes unable to keep track of Thunderbird windows, and the window switcher can't launch any more.
Hm, for me it's not intermittent at all. It happens as soon as I've sent a single message using Thunderbird; Gnome Shell simply becomes unable to keep track of Thunderbird windows, and the window switcher can't launch any more.