gnubg: add desktop item

pkgs/games/gnubg/default.nix

···
-{ lib, stdenv, fetchurl, pkg-config, glib, python3, gtk2, readline }:
+{ lib, stdenv, fetchurl, pkg-config, glib, python3, gtk2, readline,
+  copyDesktopItems, makeDesktopItem }:
 
 stdenv.mkDerivation rec {
   pname = "gnubg";
···
     hash = "sha256-cjmXKUGcrZ8RLDBmoS0AANpFCkVq3XsJTYkVUGnWgh4=";
   };
 
-  nativeBuildInputs = [ pkg-config python3 glib ];
+  nativeBuildInputs = [ copyDesktopItems pkg-config python3 glib ];
 
   buildInputs = [ gtk2 readline ];
 
   strictDeps = true;
 
   configureFlags = [ "--with-gtk" "--with--board3d" ];
+
+  desktopItems = makeDesktopItem {
+    desktopName = "GNU Backgammon";
+    name = pname;
+    genericName = "Backgammon";
+    comment = meta.description;
+    exec = pname;
+    icon = pname;
+    categories = [ "Game" "GTK" "StrategyGame" ];
+  };
 
   meta = with lib;
     { description = "World class backgammon application";