What kind of GUIs are there for SDL?
There are several GUI libraries available from the SDL libraries page. There is also a demo on the SDL demos page of using GTk natively with SDL, which works really well for graphics output. Also on the demos page is a hack written by Kent Mein using Tcl/Tk with SDL. You may also be able to get other GUI’s to work with SDL. Many of them have documentation on how to get the toolkits to work with other applications.