I got my basic GUI code finished. Enough to be moderately functional and thats all I really need at the moment - I don't need an advanced GUI system for this game, only enough to handle some basic Maul Ball-esque menus. I'll learn from this and see how it works out.
I started the sound code today. I've never had much trouble with sound in my games to date because they've always been very simple. Play the music and shoot off a few sound effects when something interesting happens. This game won't be much different so the sound code shouldn't take me that long to code. The engine is coming together well. Two or three days and I'll be able to begin testing the engine and making the game.
I did make one discovery though. I'm going to have to learn OpenGL. I was going to anyway but I was reading the Garage Games publishing faq and it said that a significant ammount of its sales are from Mac users and that Mac users are very receptive to indie games in general. I'm going to keep my current engine for 2d games but when I get a chance, hopefully after this game is finished, I'll be able to work on an OpenGL 3d engine.