ScrollViewer Scrolling control for Windows phone 7 - windows-phone-7

Question

I have to insert elements to a itemscontrol at top of the list. While inserting an element to the list at 0th position, list is scrolling to that item. But i don't want to scroll the item to the top of the list, when an element is inserted. Any ideas for making this possible.
Code of xaml :
<Grid x:Name="LayoutRoot" Background="Transparent">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<!--TitlePanel contains the name of the application and page title-->
<StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
<TextBlock x:Name="ApplicationTitle" Text="MY APPLICATION" Style="{StaticResource PhoneTextNormalStyle}"/>
<TextBlock x:Name="PageTitle" Text="page name" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
<Button Height="72" Content="Add More" Click="Button_Click"/>
</StackPanel>
<!--ContentPanel - place additional content here-->
<ScrollViewer x:Name="MainScrollViewer" Grid.Row="1" Margin="12,0,12,0" >
<Grid x:Name="ContentPanel" >
<ItemsControl x:Name="MainItemsControl" ItemsSource="{Binding}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<TextBlock Margin="10" Text="{Binding Item}" FontSize="28" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Grid>
</ScrollViewer>
</Grid>
My class Code:
public partial class MainPage : PhoneApplicationPage
{
private ObservableCollection<Model> mainList;
public ObservableCollection<Model> MainList
{
get { return mainList; }
set
{
mainList = value;
}
}
public MainPage()
{
InitializeComponent();
}
private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
{
MainList = new ObservableCollection<Model>();
AddItems(15);
ContentPanel.DataContext = MainList;
}
void AddItems(int numberIfItemsToAdd)
{
Debug.WriteLine("AddItems()");
int start = MainList.Count;
int end = start + numberIfItemsToAdd;
for (int i = start; i < end; i++)
{
Model model = new Model();
model.Item="Item" + i;
MainList.Insert(0, model);
}
}
private void Button_Click(object sender, RoutedEventArgs e)
{
AddItems(1);
}
}
Thank you in advance.