You are probably talking about clx. When talking about GUI libraries, I was more thinking about high-level libraries, which for example bind to Gtk, Qt or Tk. T

You are probably talking about clx. When talking about GUI libraries, I was more thinking about high-level libraries, which for example bind to Gtk, Qt or Tk. There are plenty of those libraries, and that is good. But I would have liked, if the SBCL maintainers had worked together with one of the maintainers of those libraries with the goal of eventually distributing it with SBCL. So there would be a default library to target when developing tools like e.g. a graphical debugger. Today, quicklist solves a lot of dependency problems, but having an "official" GUI library could have stimulated development of more UI tools around SBCL.