anchor.diff:      + optionalString withMesa "${mesa}/lib ";
   
     # Work around a bug in configure.
  -  NIX_CFLAGS_COMPILE = "-DHAVE_X11_XLIB_H=1";
  +  NIX_CFLAGS_COMPILE = [ "-DHAVE_X11_XLIB_H=1" "-lX11" "-lcairo" ];
   
     preConfigure = "
       substituteInPlace configure --replace 'SEARCH_INCLUDE=' 'DUMMY_SEARCH_INCLUDE='
  
positive.code: { stdenv, fetchurl, pkgconfig, gtk, libXinerama, libSM, libXxf86vm, xf86vidmodeproto
  , gstreamer, gst_plugins_base, GConf
  , withMesa ? true, mesa ? null, compat24 ? false, compat26 ? true, unicode ? true,
  }:
  
  
negative.code:     sha256 = "1l1w4i113csv3bd5r8ybyj0qpxdq83lj6jrc5p7cc10mkwyiagqz";
    };
  
    buildInputs = [ gtk libXinerama libSM libXxf86vm xf86vidmodeproto gstreamer gst_plugins_base GConf libX11 cairo ]
      ++ optional withMesa mesa;
  
    nativeBuildInputs = [ pkgconfig ];
  