WPF C#

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="WPF" Height="300" Width="300">
    
        
            
            
            
            
            
                
            
            
                
                
                
                
            
            
                
                
            

        
        
    

//File:Window.xaml.cs
using System.Windows;
using System.Windows.Controls;
namespace WpfApplication1
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }
        private void InnerListBoxItem_Selected(object sender, RoutedEventArgs e)
        {
            ListBoxItem item = e.OriginalSource as ListBoxItem;
            if (item != null)
            {
                MessageBox.Show(item.Content + " was selected.", Title);
            }
        }
        private void OuterListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            object item = outerListBox.SelectedItem;
            if (item == null)
            {
                txtSelectedItem.Text = "No item currently selected.";
            }
            else
            {
                txtSelectedItem.Text = item.ToString();
            }
        }
    }
}