added Windows UI 3 blank application

HarmonyWinUI/App.xaml.cs

@@ -0,0 +1,50 @@
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Controls.Primitives;
+using Microsoft.UI.Xaml.Data;
+using Microsoft.UI.Xaml.Input;
+using Microsoft.UI.Xaml.Media;
+using Microsoft.UI.Xaml.Navigation;
+using Microsoft.UI.Xaml.Shapes;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Windows.ApplicationModel;
+using Windows.ApplicationModel.Activation;
+using Windows.Foundation;
+using Windows.Foundation.Collections;
+
+// To learn more about WinUI, the WinUI project structure,
+// and more about our project templates, see: http://aka.ms/winui-project-info.
+
+namespace HarmonyWinUI
+{
+	/// <summary>
+	/// Provides application-specific behavior to supplement the default Application class.
+	/// </summary>
+	public partial class App : Application
+	{
+		private Window? _window;
+
+		/// <summary>
+		/// Initializes the singleton application object.  This is the first line of authored code
+		/// executed, and as such is the logical equivalent of main() or WinMain().
+		/// </summary>
+		public App()
+		{
+			InitializeComponent();
+		}
+
+		/// <summary>
+		/// Invoked when the application is launched.
+		/// </summary>
+		/// <param name="args">Details about the launch request and process.</param>
+		protected override void OnLaunched(Microsoft.UI.Xaml.LaunchActivatedEventArgs args)
+		{
+			_window = new MainWindow();
+			_window.Activate();
+		}
+	}
+}