Well, reinstalling hildon-theme-alpha was the very first thing I tried (see post #1). I also tried beta but I don't remember whether I tried switching there and back. And I reinstalled libgtk2.0-common last night because it had an update (to thumb).

Never mind, I can live with it. The important thing is that everything else seems to work fine.

Thanks for your experiments with the PIN request. I had noticed the /var/run/pin-query-done file and tried deleting it but with results similar to yours.