private void ButtonOpen_Click(object sender, RoutedEventArgs e) { Storyboard storyboard = new Storyboard(); DoubleAnimation daWidth = new DoubleAnimation(SideMenu.ActualWidth, 200, new Duration(TimeSpan.FromSeconds(0.4))); storyboard.Children.Add(daWidth); Storyboard.SetTarget(daWidth, SideMenu); Storyboard.SetTargetProperty(daWidth, new PropertyPath(WidthProperty)); SideMenu.BeginStoryboard(storyboard); SideMenu.Focus(); }