anchor.diff:  { stdenv, fetchFromGitHub, autoconf, automake, boost
  -, zlib, libpng, libjpeg, libtiff
  +, zlib, libpng, libjpeg, libtiff, x11, SDL
   }:
   
   stdenv.mkDerivation rec {
  
positive.code:   };
  
  
    buildInputs = [ autoconf automake boost zlib libpng libjpeg libtiff ];
  
    # the installPhase wants to put files into $HOME. I let it put the files
    # to $TMPDIR, so they don't get into the $out
  
negative.code:                  sed -i -e 's/^povgroup.*/povgroup=nogroup/' Makefile.{am,in}
                 '';
  
    configureFlags = [ "COMPILED_BY='nix'" "--with-boost-thread=boost_thread" "--with-x" ];
  
    enableParallelBuilding = true;
    
  