WPF C# Tutorial

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
    public class MainClass : Window
    {
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new MainClass());
        }
        public MainClass()
        {
            Button btn = new Button();
            btn.HorizontalAlignment = HorizontalAlignment.Center;
            btn.VerticalAlignment = VerticalAlignment.Center;
            btn.Command = ApplicationCommands.Paste;
            btn.Content = ApplicationCommands.Paste.Text;
            Content = btn;
            CommandBindings.Add(new CommandBinding(ApplicationCommands.Paste,PasteOnExecute, PasteCanExecute));
        }
        void PasteOnExecute(object sender, ExecutedRoutedEventArgs args)
        {
            Title = Clipboard.GetText();
        }
        void PasteCanExecute(object sender, CanExecuteRoutedEventArgs args)
        {
            args.CanExecute = Clipboard.ContainsText();
        }
        protected override void OnMouseDown(MouseButtonEventArgs args)
        {
            base.OnMouseDown(args);
            Title = "title";
        }
    }