anchor.diff:  
   stdenv.mkDerivation rec {
     pname = "spice-gtk";
  -  version = "0.37";
  +  version = "0.40";
   
     outputs = [ "out" "dev" "devdoc" "man" ];
   
     src = fetchurl {
  -    url = "https://www.spice-space.org/download/gtk/${pname}-${version}.tar.bz2";
  -    sha256 = "1drvj8y35gnxbnrxsipwi15yh0vs9ixzv4wslz6r3lra8w3bfa0z";
  +    url = "https://www.spice-space.org/download/gtk/${pname}-${version}.tar.xz";
  +    sha256 = "sha256-I/X/f6gLdWR85zzaXq+LMi80Mtu7f286g5Y0YYrbztM=";
     };
   
     postPatch = ''
       # get rid of absolute path to helper in store so we can use a setuid wrapper
       substituteInPlace src/usb-acl-helper.c \
         --replace 'ACL_HELPER_PATH"/' '"'
  +    # don't try to setcap/suid in a nix builder
  +    substituteInPlace src/meson.build \
  +      --replace "meson.add_install_script('../build-aux/setcap-or-suid'," \
  +      "# meson.add_install_script('../build-aux/setcap-or-suid',"
     '';
   
     nativeBuildInputs = [
  
positive.code:     gtk3
      json-glib
      libcacard
      libdrm
      libjpeg_turbo
      libopus
  
negative.code: , python3
  , spice-protocol
  , usbredir
  , vala
  , wayland-protocols
  , zlib
  , withPolkit ? true
  }:
  