Very nice program. I've been using it for a bit, and I enjoy it, especially due to its simplicity and lack of nonsense.
I think we need to start cataloging the secrets, though. I've been way too curious. Has anypony discovered anything? Do we have any leads?
So far, here's what has been found:
-Scootaloo theme. A screenshot is in the OP, but we don't as of yet know how to get there.
-HP text. Mentioned by >>874491, screenshot in >>874493. Can anypony else with an HP computer confirm that this happens on their computer?
We know that there are at least 5 secret themes.