Sorry, I put this in the wrong forum accidentally. This is the right place for it.
There’s a lot of restarting involved in switching themes, and a lot of users will be testing the themes out to find the one they like.
I suggest adding a Restart command to the File menu that close and reopens the program in one go. This cuts out the manual relaunch step, which gets tedious after the third or fourth time doing it. After all, there are eight themes so far in the beta. A Restart command would save a lot of time for anyone who wants to see what they all look like.