private void btnNextPage2_Click(object sender, RoutedEventArgs e)
        {
            Page2 page = new Page2("I've been passed this text");

            NavigationService ns = this.NavigationService;

            ns.Navigate(page);
        }
        private void btnNextPage_Click(object sender, RoutedEventArgs e)
        {
            Page2 page = new Page2();

            NavigationService ns = this.NavigationService;

            ns.Navigate(page);
        }