Very nice addition, Steven.
I do find one aspect of it that isn't working as -I- expected it to, and am not sure if it's a bug, or the intended behavior.
I select 'non-square artwork' (for example) and edit the album art that is now square. At first I expected it to disappear as the artwork is now square. When it didn't drop off the list, I clicked 'refresh' thinking that would clear it from the list. But it doesn't. The behavior is the same no matter which search options are selected.
I think it would be more useful if the artwork is edited to exceed the criteria searched, then it should disappear. Ideally automatically, but if not, then at least with the refresh.