Thanks to both of you.
I'm implementing a MUD-like console game, which is, unfortunately, looking more and more like it is not a good match for SGML, since it mostly deals with text. It's kind of a hard match for any graphics lib, however. I've been using pdcurses, but the problem there is that the event system is blocking, so I can't poll for keyboard events (not to mention that we'd like to use sprites for inventory items).
Anyway, that's just a little background on where I'm coming from.
I've tried out Allegro, SGML, and SDL, and I like SGML the best so far... but I may have to just wait to use it for my next project, which will hopefully get into the graphics realm.
Thanks again, and keep up the excellent work!