anchor.diff:  { fetchurl, stdenv, python2Packages, makeWrapper, lib
  -, xpdf, mesa, freeglut }:
  +, xpdf, mesa, SDL, freeglut }:
   
   let
     inherit (python2Packages) python pyopengl pygame setuptools pillow;
  -  version = "0.10.5";
  +  version = "0.11.1";
   in stdenv.mkDerivation {
       # This project was formerly known as KeyJNote.
       # See http://keyj.s2000.ws/?p=77 for details.
  
positive.code: 
      src = fetchurl {
        url = "mirror://sourceforge/impressive/Impressive-${version}.tar.gz";
        sha256 = "0fz1zahxlfjang53wn06svy4s4aw28c79v24gwadvjvv3h1g5wam";
      };
  
      # Note: We need to have `setuptools' in the path to be able to use
  
negative.code:       # honors $LIBRARY_PATH.  See
        # http://python.net/crew/theller/ctypes/reference.html#id1 .
        wrapProgram "$out/bin/impressive" \
           --prefix PATH ":" "${xpdf}/bin" \
           --prefix PYTHONPATH ":" \
                    ${lib.concatStringsSep ":"
                       (map (path:
                              path + "/lib/${python.libPrefix}/site-packages")
                            [ pillow pyopengl pygame setuptools ])} \
           --prefix LIBRARY_PATH ":" "${lib.makeLibraryPath [ mesa freeglut SDL ]}"
      '';
  
      meta = {
  