WPF C# Tutorial

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
    public class MainWindow : Window
    {
        Button btn = new Button();
        [STAThread]
        public static void Main()
        {
            Application app = new Application();
            app.Run(new MainWindow());
        }
        public MainWindow()
        {
            btn.Content = "Expanding Button";
            btn.FontSize = 12;
            btn.HorizontalAlignment = HorizontalAlignment.Center;
            btn.VerticalAlignment = VerticalAlignment.Center;
            btn.Click += ButtonOnClick;
            Content = btn;
        }
        void ButtonOnClick(object sender, RoutedEventArgs args)
        {
            DoubleAnimation anima = new DoubleAnimation();
            anima.Duration = new Duration(TimeSpan.FromSeconds(2));
            anima.From = 12;
            anima.To = 48;
            anima.FillBehavior = FillBehavior.Stop;
            btn.BeginAnimation(Button.FontSizeProperty, anima);
        }
    }