Comment 70 for bug 1181666

I just had again a similar problem with current Ubuntu and Gnome 3: mouse left clicks and terminal focus did not work. Alt-F2 including command input and Alt-tab worked but super-tab did not (maybe I use some non-standard setting here).

I also had the "Workspace Indicator" (but not "Workspaces-to-dock") extension installed (which I meanwhile disabled just to be on the safe side). Yet I suspect that in my case the symptom was raised by an occasional and for the most time hidden psensor popup window "Authentication is required to update SMART data from /dev/sda" asking (for some weird reason) for root password input - see also https://forums.mauilinux.org/showthread.php?tid=24357 how to disable that)

Not being able to use the system due to some bug is one of the worst user experiences. Such a thing drives people nuts and can easily destroy the reputation of Ubuntu/Gnome etc. A stable user interface should have high priority. I suggest re-designing gnome-shell such that it cannot be blocked by any (misbehaving) application or extension.