vassal: add desktop entry

pkgs/by-name/va/vassal/package.nix

@@ -6,6 +6,8 @@
   jre,
   makeWrapper,
   wrapGAppsHook3,
+  makeDesktopItem,
+  copyDesktopItems,
   versionCheckHook,
 }:
 
@@ -25,6 +27,7 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [
     makeWrapper
     wrapGAppsHook3
+    copyDesktopItems
   ];
 
   installPhase = ''
@@ -40,9 +43,23 @@ stdenv.mkDerivation rec {
       --add-flags "-Duser.dir=$out -cp $out/share/vassal/Vengine.jar \
       VASSAL.launch.ModuleManager"
 
+    install -Dm444 -t "$out/share/icons/hicolor/scalable/apps/" VASSAL.svg
+
     runHook postInstall
   '';
 
+  desktopItems = [
+    (makeDesktopItem {
+      name = "VASSAL";
+      exec = "vassal";
+      icon = "VASSAL";
+      desktopName = "VASSAL";
+      comment = "The open-source boardgame engine";
+      categories = [ "Game" ];
+      startupWMClass = "VASSAL-launch-ModuleManager";
+    })
+  ];
+
   # Don't move doc to share/, VASSAL expects it to be in the root
   forceShare = [
     "man"