anchor.diff: -{ fetchurl, stdenv, pkgconfig, cairo, xlibsWrapper, fontconfig, freetype, libsigcxx }:
  +{ fetchurl, stdenv, pkgconfig, darwin, cairo, xlibsWrapper, fontconfig, freetype, libsigcxx }:
   let
     ver_maj = "1.12";
     ver_min = "0";
  
positive.code: 
    nativeBuildInputs = [ pkgconfig ];
    propagatedBuildInputs = [ cairo libsigcxx ];
    buildInputs = [ fontconfig freetype ];
  
    doCheck = true;
  
  
negative.code:     homepage = http://cairographics.org/;
  
      license = with licenses; [ lgpl2Plus mpl10 ];
      platforms = platforms.unix;
    };
  }
  