anchor.diff:    mesaSupported =
       system == "i686-linux" ||
       system == "x86_64-linux" ||
  +    system == "x86_64-darwin" ||
       system == "i686-darwin";
   
     mesa = import ../development/libraries/mesa {
  
positive.code:       libpng libjpeg libungif libtiff texinfo dbus;
      inherit (xlibs) libXaw libXpm libXft;
      inherit (gtkLibs) gtk;
      xawSupport = system == "i686-darwin" || getPkgConfig "emacs" "xawSupport" false;
      xaw3dSupport = getPkgConfig "emacs" "xaw3dSupport" false;
      gtkGUI = getPkgConfig "emacs" "gtkSupport" true;
      xftSupport = getPkgConfig "emacs" "xftSupport" true;
  
negative.code:     inherit fetchurl stdenv texinfo perl
              gnused groff libxml2 libxslt makeWrapper;
      inherit (perlPackages) XMLSAX XMLParser XMLNamespaceSupport;
      libiconv = if stdenv.isDarwin then libiconv else null;
    };
  
    dosfstools = composedArgsAndFun (import ../tools/misc/dosfstools) {
  