Hi Mark,
I am inclined to agree - there is something nice about just being able to type and have the filter applied. There's no obvious filter text applied to dropdown select boxes but many people have learned that you can search those in a similar fashion themselves.
Initially this would only apply to chooser dialogues, and at present there is only the activity chooser.
Plans are afoot already to replace the existing question bank chooser so that would also become searchable. I've also been looking at creating a block searcher.
I'd like to work on a few other areas to improve the interfaces, and this would likely be a part of that. I've been specifically considering the manual enrolment pages so far, but I've not done any work there yet (all pie in the sky thought).
Thanks,
Andrew