silverlight - How to use ComboBox SelectionChanged event

how to use ComboBox SelectionChanged event in silverlight
MainPage.xaml

<UserControl 
    x:Class="SilverlightApps.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="600" 
    d:DesignWidth="800" 
    xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
    >

    <Grid x:Name="LayoutRoot" Background="White">
        <Rectangle
            Name="rectangle1"
            Fill="AliceBlue" 
            HorizontalAlignment="Left" 
            Height="82" 
            Margin="20,12,0,0" 
            Stroke="Black" 
            VerticalAlignment="Top" 
            Width="600"
            StrokeThickness="0"
            />

        <TextBlock 
      Height="82" 
      HorizontalAlignment="Left" 
      Margin="20,9,0,0" 
      Name="textBlock1" 
      Text="how to use ComboBox SelectionChanged event in silverlight"
      VerticalAlignment="Top"
      TextWrapping="Wrap"
      FontSize="20"
      FontStyle="Italic"
      Foreground="MidnightBlue"
      Width="600"
      FontFamily="Comic Sans MS"
      Padding="25,10,0,0"
            />

        <ComboBox 
      Height="23" 
      HorizontalAlignment="Left" 
      Margin="31,130,0,0" 
      Name="comboBox1" 
      VerticalAlignment="Top" 
      Width="188" 
            SelectionChanged="comboBox1_SelectionChanged" 
            >
            <ComboBoxItem Content="Arabian Coffee"/>
            <ComboBoxItem Content="Armadillo Fruit"/>
            <ComboBoxItem Content="Australian Finger Lime"/>
            <ComboBoxItem Content="Bahia Sunsapote"/>
            <ComboBoxItem Content="Batoko Plum"/>
        </ComboBox>

        <TextBlock 
            Name="textBlock2"
            HorizontalAlignment="Left" 
            Height="23" 
            Margin="265,130,0,0" 
            TextWrapping="Wrap" 
            Text="Select A ComboBox Item" 
            VerticalAlignment="Top" 
            Width="326"
            FontSize="15"
            Foreground="DeepPink"
            />
    </Grid>
</UserControl>
MainPage.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace SilverlightApps
{
    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();
        }

        private void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            ComboBoxItem cbi = (sender as ComboBox).SelectedItem as ComboBoxItem;
            textBlock2.Text = "you selected: ";
            textBlock2.Text += cbi.Content.ToString();
        }
    }
}
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