anchor.diff:  { stdenv, fetchurl, pkgconfig, gettext, perl
   , expat, glib, cairo, pango, gdk_pixbuf, atk, at_spi2_atk, gobjectIntrospection
  -, xorg, wayland, epoxy, json_glib, libxkbcommon, gmp
  +, xorg, epoxy, json_glib, libxkbcommon, gmp
  +, waylandSupport ? stdenv.isLinux, wayland, wayland-protocols
   , xineramaSupport ? stdenv.isLinux
   , cupsSupport ? stdenv.isLinux, cups ? null
   , darwin
  
positive.code:     "--disable-glibtest"
      "--with-gdktarget=quartz"
      "--enable-quartz-backend"
    ];
  
    postInstall = ''
  
negative.code:   propagatedBuildInputs = with xorg; with stdenv.lib;
      [ expat glib cairo pango gdk_pixbuf atk at_spi2_atk
        libXrandr libXrender libXcomposite libXi libXcursor libSM libICE ]
      ++ optionals waylandSupport [ wayland wayland-protocols ]
      ++ optional stdenv.isDarwin (with darwin.apple_sdk.frameworks; [ AppKit Cocoa ])
      ++ optional xineramaSupport libXinerama
      ++ optional cupsSupport cups;
  