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:     pixman
      spice-protocol
      usbredir
      zlib
    ] ++ lib.optionals withPolkit [ polkit acl usbutils ] ;
  
    PKG_CONFIG_POLKIT_GOBJECT_1_POLICYDIR = "${placeholder "out"}/share/polkit-1/actions";
  
    mesonFlags = [
      "-Dcelt051=disabled"
      "-Dpulse=disabled" # is deprecated upstream
    ];
  
    meta = with lib; {
  
negative.code: , gst_all_1
  , gtk-doc
  , gtk3
  , hwdata
  , json-glib
  , libcacard
  , libcap_ng
  , libdrm
  , libjpeg_turbo
  , libopus
  