"working" throbber for typeahead

Created by: atuttle

When a typeahead control's source requires an API hit, it could be some significant amount of time -- I'd say even just a half second is enough to be considered significant -- before results are displayed. It would be nice if there were a throbber displayed over top of the input. Maybe something like this:

Of course you'd want to be able to enable/disable the feature (off by default).