S2DL is a set of class based wrappers for SDL. It does not at the moment include a GUI but it can be created reasonably easily.

S2DL v 1.10 includes Graphics, Font and Screen Classes.

There is also an AI class wrapping DWS (so only available on Windows) and in progress is a state class.

Also there is a set of controls called SDLControls (I think) that is a graphically bases GUI for SDL. (Personally I did not like it very much).