Is there a simple way to create a filter that takes songs from certain filters, but not from others?  For instance, I want songs that match filters "A", "B", or "C", but not filter "D" and "E".  Right now, simply highlighting filters "A", "B", and "C" will give me the union (or intersection) of the 3 filters, but I would like to subject this "new" filter to further constraints.

I know I can filter based on membership of lists, so it might be something as simple as adding the ability based on membership of filters, but I'm not sure how to add that functionality...

It's not currently possible, I'll think about adding it, it shouldn't be too hard I guess.