The backend are implemented “behind” CLIM itself: McClim is designed to abstract over multiple rendering backends. For a while the X backend was the only one that was ready, but I think there’s ongoing projects for a Windows and a Gtk/Cairo backend right now.
> Climacs depends on McCLIM for its graphic user interface. Second Climacs is independent of any particular library for making graphic user interfaces, allowing it to be configured with different such libraries. Though, at the moment, the only graphic user interface that exists uses McCLIM
