The options for what is supposed to be chosen is actually inversed. So you choose arcade and it hides all arcade titles. Very odd.
Upon choosing to hide MESS entries under the available folder I still get roms listed even though I don't have them in my roms folder such as TTL games eg. Breakout (TTL)
I'd want to hide those too but I don't see how.
I wish this feature didn't change as its adding complexity for no good reason.