My first four GUI elements! Top to bottom:
Switch - A box that can be filled or empty.
Button - A simple button that knows when it's tapped.
Pick one - Linked boxes. Only one is active at a time.
Text box - A field for entering text.
It's going to need some polish before it's ready for prime time. And I'm sure I'd like to leave some of the more involved elements like dropdown boxes to the true professionals. But is there anything obvious and useful that I've missed?
(One thing I still plan to make is a rotating text field that changes every time you tap it, for choices like "Human/CPU/Off" and so on.)