Effects Masking UI
Effects masking is super-powerful feature, but apparently there's no UI to it it in the Effects Controls as one would assume, and that would make it easy to use. Instead one has to scroll and twirl one's way down in the timeline to add masks to effects. And then, there's no Inverse checkbox, so for a lot of even simple things, one has to make two identical masks, one Add and one Subtract. That's a ridiculous oversight. There should be a full apply mode popup for each effects mask.
