private void button1_Click(object sender, RoutedEventArgs e)
        {
            Thread thread = new Thread(UpdatePosition);
            thread.Start();
        }


        private void UpdatePosition()
        {
            
            for (int i = 0; i <= 45; i++)
            {

                this.Dispatcher.BeginInvoke(
                    DispatcherPriority.Normal, 
                    (ThreadStart)delegate()
                        {
                            RotateTransform rtf = new RotateTransform(i);
                            rtf.Freeze();
                            label1.RenderTransform = rtf; 
                        }
                        );

                Thread.Sleep(100);
            }
        }