Comment 4 for bug 943851

Confirmed. Unfortunately Alt presently triggers an active synchronous keyboard grab, in order to tell the difference between Alt taps and Alt+other_key. This grab sends events causing the current widget to lose focus.

The only two solutions to this bug I can think of are:

1. Don't bind the lone "Alt" key to the HUD in Unity 5. This is a Unity team design decision.

2. Rewrite the tapping detection in compiz to not use active grabs. Unfortunately I have tried this several times over the past month and again today and not yet succeeded.