Fix flake and make runner script run code as WM

flake.nix

@@ -50,8 +50,6 @@
         buildInputs = with pkgs; [
           libxcb
           xcbutilwm
-          xrandr
-          xprop
           ocamlPackages.ctypes
           ocamlPackages.ctypes-foreign
           mruby
@@ -76,6 +74,32 @@
         mruby = mruby;
       };
 
+      apps.${system}.default = {
+        type = "app";
+        program = "${pkgs.writeShellScript "kutu-run" ''
+          set -e
+          if [ -z "$DISPLAY" ]; then
+            exec ${pkgs.xinit}/bin/startx \
+              ${kutu}/bin/kutu \
+              -- \
+              ${pkgs.xorg-server}/bin/X
+          else
+            DISPLAY_NUM=:100
+            ${pkgs.xorg-server}/bin/Xephyr \
+              $DISPLAY_NUM \
+              -screen 1280x720 \
+              -ac \
+              > /tmp/kutu-xephyr.log 2>&1 &
+            XEPHYR_PID=$!
+            cleanup() { kill "$XEPHYR_PID" 2>/dev/null || true; }
+            trap cleanup EXIT INT TERM
+            sleep 1
+            DISPLAY=$DISPLAY_NUM ${kutu}/bin/kutu
+            echo "Returned: $?"
+          fi
+        ''}";
+      };
+
       devShells.${system}.default = pkgs.mkShell {
         inputsFrom = [ kutu ];