Anderton
I think the reason why it's not obvious is that graphically, it appears the tracks are a subset of the folder. But functionally, a folder is just a way to organize tracks - they can be MIDI, audio, or instruments. So when you save the tracks, you save the folder that organizes them.
That's a classic example, I think, of the difference between a user model, and a developer model.
In terms of usage, tracks *are* a subset of the folder. Conceptually, visually, everything. That is, seen from a user's point of view.
Now, the way to
implement that in code is almost certainly as you describe, but that's kind of immaterial. It's so utterly counter intuitive from a user point of view to think that way.