i have installed gtk for Haskell Platform 2010.2 on windows xp, it is working okay,  now i want to use gtk with opengl ,  it is said that i must install gtk2hs with --enable-opengl  flag,  but how to do that for ms windows ? "cabal install gtk --enable-opengl" are not acceptable. at the beginning i have installed gtk using "cabal install gtk". any help appreciated