anchor.diff:  
     libXi = super.libXi.overrideAttrs (attrs: {
       outputs = [ "out" "dev" "man" "doc" ];
  -    propagatedBuildInputs = attrs.propagatedBuildInputs or [] ++ [ self.libXfixes self.libXext ];
  +    propagatedBuildInputs = attrs.propagatedBuildInputs or [] ++ [ xorg.libXfixes xorg.libXext ];
       configureFlags = lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
         "xorg_cv_malloc0_returns_null=no"
       ] ++ lib.optional stdenv.hostPlatform.isStatic "--disable-shared";
  
positive.code: 
    libXft = super.libXft.overrideAttrs (attrs: {
      outputs = [ "out" "dev" ];
      propagatedBuildInputs = attrs.propagatedBuildInputs or [] ++ [ self.libXrender freetype fontconfig ];
      configureFlags = attrs.configureFlags or []
        ++ malloc0ReturnsNullCrossFlag;
  
  
negative.code:     postInstall =
        ''
          mkdir -p $out/share/man/man7
          ln -sfn ${xorg.xkeyboardconfig}/etc/X11 $out/share/X11
          ln -sfn ${xorg.xkeyboardconfig}/share/man/man7/xkeyboard-config.7.gz $out/share/man/man7
        '';
    });
  
  