Today, I continued work on the level editor component of my C++ port of Rainbow. While it isn't as pretty as it could be, it now is entirely functional, and ready to build levels with.
Here's what a little test level looks like in the editor and in the game. Note that the grey box in the lower right of the game view is a button that brings up a "restart/quit" menu -- useful to have so you can get back to the editor.
All that remains is to get peon placement and load/save looped in, and then I should be able to realize my goal of being able to build Rainbow levels "on the go". (Hmm, I wonder how I can get the files back off my phone? I should make sure there's a section for that in the XCode organizer. I think there is.)