McCLIM: A GUI Toolkit for Common Lisp
Blast from the past!  I used to work on McCLIM and Climacs as an impressionable youth almost ten years ago.  I think the battle for coming up with new ways of defining GUIs is lost (and the web is eating everything anyway), but CLIM was definitely an interesting idea.  While it lost a bit in the ability of individual applications to customise their behaviour, it won a lot in the interoperability that was transparently provided by the presentation system.  Using &quot;presentations&quot;, any on-screen object could be associated with a Lisp object.  An application would usually &quot;present&quot; various objects using &quot;presentation types&quot; (image, graph, filename, etc), and other applications could then &quot;accept&quot; input of a given presentation type.  If some object of an acceptable type was somewhere on the screen, the user could just click it.  Text-based input entry was usually also permitted, assuming the presentation type in question had a textual representation.<p>I mostly worked on Drei, which was the input editor.  It finds use in Climacs (which is probably not worth using if you have Emacs), and the McCLIM Listener, which <i>is</i> really cool.  It shows the potential of adding bits of graphics support to a classical REPL, and being able to work interactively with opaque objects.<p>Using CLIM is a bit like operating an artifact that somehow made its way from an alternative universe.