1) Sound in Linux is a very obscure world. There are al least two kind of kernel drivers (OSS, Alsa), there are lot of sound servers (Arts and ESound are the most known), lot of mixers, etc. May be SDL is good option to enable sound on Gambas, but we should be sure it is compatible with, at least the more common sound subsystems in Linux (I really mean, Linux, FreeBSD, etc), and I don't kwnow if it is true at this moment. About Linux sound problems, for instance, I usually play DVDs with Xine (unencrypted, of course , and some days sound goes OK, some days I have to stop Arts first... randomly, may be sound is still an unstable world on Linux (or may be it is problem of Mandrake and RedHat, I'm not sure)
2) Midi : lot of PCI cards has still a bad midi support on Linux, however there are emultators, like timidity, that "parses" midi into wav, that are quite useful to play midis on not supported cards, Gambas sound developers should care about this fact to let more people use Gambas-midi programs.
3) SDL graphics (that's the part I know) is a very low-level implementation, you can just create surfaces (rectangles), no way to draw polygons, circles, etc, directly. May be a Gambas implementation should support at least the more common primitives. By other said, SDL windows seems to be always "stand-alone" windows, may be it would be necessary to implement SDL like a component you can just put in your window, like a button or a picture box, but I don't if it is possible.
4) There's another interesting library, DirectFB (www.directfb.org) which provides a framebuffer and hardware acceleration without X servers. It would be very interesting in order to let people program with Gambas in little devices (few memory, few resources) which can't handle a full X server. There's also a GTK-DirectFB implementation, so a GTK component would be very useful in both worlds (X-DirectFB)
5) May be OpenGL (Mesa) is also a point to be implemented in Gambas, it would be nice a 3D studio made with Gambas.
Interesting comments. I'd like to hear from the SDL component author!