private void btnResizeTo_Click(object sender, RoutedEventArgs e) { var rect = new Rectangle() { Height = 250, Width = 350, Fill = new SolidColorBrush(Colors.Blue) }; MainStage.Children.Add(rect); rect.SetPosition(50, 50); rect.ResizeTo(150, 150, 1.5.seconds()) .WhenComplete(a => { Thread.Sleep(2000); MainStage.Children.Remove(rect); }) .Begin(); }