how to insert ComboBox Item at list first (list prepend) programmatically in silverlight

Introduction

I will explain how to insert ComboBox Item at list first (list prepend) programmatically in silverlight
Example

<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                  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"       x:Name="textBlock1"       Text="how to insert ComboBox Item at list first (list prepend) programmatically 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="132,112,0,0"       x:Name="comboBox1"       VerticalAlignment="Top"       Width="120"                >                  <ComboBoxItem Content="Brazilian Guava"/>                  <ComboBoxItem Content="Brunei Cherry"/>                  <ComboBoxItem Content="Candle Stick Tree"/>                  <ComboBoxItem Content="Copacabana Guava"/>            </ComboBox>            <Button       Content="Insert ComboBox New Item At List First [Egg Fruit]"       Height="23"       HorizontalAlignment="Left"       Margin="39,277,0,0"       x:Name="button1"       VerticalAlignment="Top"       Click="button1_Click" Width="328"                />       </Grid> </UserControl>

 
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 button1_Click(object sender, RoutedEventArgs e)         {             ComboBoxItem cbi = new ComboBoxItem();             cbi.Content = "Egg Fruit";             //this line insert combobox new item at list first             comboBox1.Items.Insert(0, cbi);         }     } }