anchor.diff: -{ lib, stdenv, fetchurl, tcl, tk, libX11, zlib, makeWrapper, makeDesktopItem }:
  +{ lib, fetchurl, tcl, tk, libX11, zlib, makeWrapper, makeDesktopItem }:
   
  -stdenv.mkDerivation rec {
  +tcl.mkTclDerivation rec {
     pname = "scid-vs-pc";
     version = "4.21";
   
  
positive.code:   };
  
    nativeBuildInputs = [ makeWrapper ];
    buildInputs = [ tcl tk libX11 zlib ];
  
    prePatch = ''
      sed -i -e '/^ *set headerPath *{/a ${tcl}/include ${tk}/include' \
  
negative.code: 
      for cmd in $out/bin/* ; do
        wrapProgram "$cmd" \
          --set TK_LIBRARY "${tk}/lib/${tk.libPrefix}"
      done
    '';
  