In correspondance with Alistair Bayley I learned that there is in fact a gtk2hs installer for 6.10.4. One can find it by Googling "gtk2hs 6.10.4" (which I did not think to do). The URL is in http://www.mail-archive.com/gtk2hs-devel@lists.sourceforge.net/msg00340.html The installer doesn't work if the Haskell Platform is installed in the default location, which has spaces in the pathname. Reinstalling Haskell in, say, c:\HaskellPlatform makes it all work.