Would it be possible to have the currently selected snapshot remain highlighted in the list while it's being tested or played?
Similarly, could the last snapshot you selected remain highlighted while you're editing? Sometimes when you're editing an interaction with a lot of snapshots it's easy to loose track of where you are in the list. Same thing for when the interaction is playing.
It would make life a little easier when you're making something complex.
On a slightly different note, I don't think it makes sense to have the 'Create new' button active when you're in play mode, as you can't do anything with, or delete, any snapshot you may create if you click on it. It's a minor thing, but it bugs me a little.