Sorry, yes, I broke it earlier today trying to implement Tilman's suggestion above, and I haven't had time to fix it.
Try "cvs up -D 2002-09-14" or something like that, that at least works.
The problem is that the only way I know to tell the form builder that you're not quite ready to submit is to do a validation error. Unfortunately, that's also somewhat ugly, and there's a problem in that the time that the validation proc is called before the widget proc, but it's the widget proc that knows that we couldn't find any users as a result of the search.
I'll try to find or create some other mechanism to tell the form that it's not done, so that "form is_valid" isn't true, and the right time to do it, before the form is rendered. Hmm, we need a message-sequence diagram for the form builder.