anchor.diff:  
     xf86videodummy = xorg.xf86videodummy.overrideDerivation (p: {
       patches = [
  +      # patch provided by Xpra upstream
         ./0002-Constant-DPI.patch
  +      # https://github.com/Xpra-org/xpra/issues/349
         ./0003-fix-pointer-limits.patch
  +      # patch provided by Xpra upstream
         ./0005-support-for-30-bit-depth-in-dummy-driver.patch
       ];
     });
  
positive.code: 
  in buildPythonApplication rec {
    pname = "xpra";
    version = "4.0.6";
  
    src = fetchurl {
      url = "https://xpra.org/src/${pname}-${version}.tar.xz";
      sha256 = "nGcvbZFGYd2nQ75LL4YN+xcWb7UsViA3OAqpcrTwieg=";
    };
  
    patches = [
      (substituteAll {
        src = ./fix-paths.patch;
        inherit (xorg) xkeyboardconfig;
        inherit libfakeXinerama;
      })
      ./fix-41106.patch
    ];
  
    postPatch = ''
      substituteInPlace setup.py --replace '/usr/include/security' '${pam}/include/security'
    '';
  
    nativeBuildInputs = [ pkg-config wrapGAppsHook ];
    buildInputs = with xorg; [
      libX11 xorgproto libXrender libXi
      libXtst libXfixes libXcomposite libXdamage
  
negative.code: { lib, fetchurl, substituteAll, python3, pkg-config, writeText
  , xorg, gtk3, glib, pango, cairo, gdk-pixbuf, atk, pandoc
  , wrapGAppsHook, xorgserver, getopt, xauth, util-linux, which
  , ffmpeg, x264, libvpx, libwebp, x265
  , libfakeXinerama
  