anchor.diff:    '';
   
     nativeBuildInputs = [ pkgconfig ];
  -  propagatedBuildInputs = [ xlibsWrapper inputproto libXi freeglut ];
  +  propagatedBuildInputs = [ inputproto ]
  +    ++ (if stdenv.isDarwin
  +        then (with darwin.apple_sdk.frameworks; [Cocoa AGL GLUT freetype libtiff])
  +        else [ xlibsWrapper libXi freeglut ]);
   
     enableParallelBuilding = true;
   
  
positive.code:   meta = {
      description = "A C++ cross-platform lightweight GUI library";
      homepage = http://www.fltk.org;
      platforms = stdenv.lib.platforms.linux;
      license = stdenv.lib.licenses.gpl2;
    };
  
  }
  
  
negative.code: { stdenv, composableDerivation, fetchurl, pkgconfig, xlibsWrapper, inputproto, libXi
  , freeglut, mesa, libjpeg, zlib, libXinerama, libXft, libpng
  , cfg ? {}
  , darwin, libtiff, freetype
  }:
  
  let inherit (composableDerivation) edf; in
  