I've uploaded a snapshot of my work on a McCLIM backend for Windows:
http://home.earthlink.net/~jdunrue/clim-graphic-forms.zip
The README in that zip file explains:
This directory contains the start of a McCLIM backend implementation for Win32 using the Graphic-Forms library. I am making this snapshot available in the hopes that someone else possessing sufficient time, motivation, and McCLIM knowledge can pick up where I've left off.
Files in this archive:
mcclim.asd -- a patched version of mcclim.asd (rev 1.39) defining a new system called :clim-graphic-forms
ports.lisp -- a patched version of ports.lisp (rev 1.53) that adds the symbol :graphic-forms to *server-path-search-order*
Backends/ Graphic-Forms/
README.txt -- this file
frame-manager.lisp -- backend code gadgets.lisp graft.lisp medium.lisp package.lisp port.lisp utils.lisp
loader.lisp -- a utility to load the system; you can either modify this to suit your local environment or just consult it as a reference
My overall plan was to use existing abstractions provided by Graphic-Forms on top of the Win32 API rather than re-implement that infrastructure. Package nicknames GFG: GFS: and GFW: identify symbols exported from that library.
Many thanks to David L., Troels, and Robert S. for their replies to my earlier queries. And thanks to Christophe for creating the null backend, without which getting started would have been much more difficult. I will be happy to answer questions or provide fixes for Graphic-Forms to facilitate further development of this backend.