As it stands, the program will only test a search against the whole archive. For reasons which are complicated, I sometimes have related topics and only want to filter against a certain archive, not against all of them. It shouldn’t be to hard to provide a option to select which archives should be filtered.
You and I like to tell developers that it shouldn’t be at all hard to add the little feature we would like to have available.
The developers, on the other hand, have a long list of changes and additions they would like to make, if only they had time. Sometimes they get grumpy (though never Christian, of course).
Actually, I think Christian mentioned the ability to filter by selected archive(s) as a possible future enhancement.
No promise or date, though.