One thing I've noticed in X3a Staff View that has changed (that I'm not sure I like) is once notes are selected, you can't click off them to deselect (like in X2a)
You have to select other notes to deselect them. I work a lot in Staff View, and it's really taking a lot of getting used to, this new behaviour.
Or is there a new default setting for note selection I can't find ?