I tried compiling the darcs version of gtk2hs with ghc 6.12 rc2.
First, the each package.conf needs an id, which it doesn't currrently have. Also, in c2hs, there is no CLDouble anymore, so you need to replace it with CDouble (http://hackage.haskell.org/trac/ghc/ticket/2793).
After doing that things seemed to be working until c2hsLocal starting working on gtk/Graphics/UI/Gtk/Selectors/FileChooser.chs. At this point, memory usage kept climbing, and the process was eventually killed (I have only 1gb ram). The strange thing is this only happens with ghc 6.12. With ghc 6,10,4, everything works (I did not see exactly how much memory was used in that case).
Any ideas? What if I were to compile c2hsLocal with ghc 6.10.4 and then compile the rest of gtk2hs with ghc6.12? Any reason this wouldn't work? Also, has anyone succesfully compiled gtk2hs with ghc 6.12? I don't want to spend more time on this only to find it is impossible.