anchor.diff:      xorg.libXpm
       libxrender
       libxres
  -    xorg.libxshmfence
  +    libxshmfence
       libxt
       libxtst
       nettle
  
positive.code:     ###ln -s /var/tmp $out/share/X11/xkb/compiled  # FIXME
  
      wrapProgram $out/bin/Xephyr \
        --set XKB_BINDIR "${xorg.xkbcomp}/bin" \
        --add-flags "-xkbdir ${xorg.xkeyboardconfig}/share/X11/xkb"
      wrapProgram $out/bin/Xvfb \
        --set XKB_BINDIR "${xorg.xkbcomp}/bin" \
        --set XORG_DRI_DRIVER_PATH ${opengl-dummy.driverSearchPath}/lib/dri \
        --add-flags "-xkbdir ${xorg.xkeyboardconfig}/share/X11/xkb"
    '';
  
    bindnow = false;
  
negative.code:     xorg.xcbutilimage
      xorg.xcbutilkeysyms
      xorg.xcbutilrenderutil
      xkbcomp
      xorgproto
      xtrans
    ];
  