There are several GUI libraries for CL. The best and most complete is Qtools (and CommonQt), which wrap Qt. IMO it makes Qt development easier in Lisp than it

There are several GUI libraries for CL. The best and most complete is Qtools (and CommonQt), which wrap Qt. IMO it makes Qt development easier in Lisp than it is in C++. Installation on Linux is super easy, just make sure the Qt libs and dev libraries are installed from your package manager, and then install with QuickLisp. On OSX it was tricky installing the Qt libs, but after that installing with QuickLisp just worked. I haven't tried on Windows, but supposedly it works for people. https://github.com/Shinmera/qtools https://github.com/Shinmera/qtools I've also used ltk a few times, and it's okay, but it's wrapping Tk, so ... I think there are also interfaces for wxWidgets and Gtk, but I've always liked Qt, so I haven't looked very hard.