test.xaml

<Page  
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"  
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"  
    xmlns:scm="clr-namespace:System.ComponentModel;assembly=WindowsBase"  
    >  
  <Grid>  
    <Grid.Resources>  
      <ResourceDictionary>  
        <!-- This retrieves and provides data to controls -->  
        <XmlDataProvider x:Key="FeedData"   
          IsAsynchronous="True" IsInitialLoadEnabled="True"  
          Source="http://tech.yahoo.com/rss/blogs;_ylt=AundRjbnFGWfXrTyBtK_6QM3LpA5"  
          XPath="//rss/channel"/>  
        <CollectionViewSource x:Key="ItemList"   
          Source="{Binding Source={StaticResource FeedData}, XPath=item}" >  
          <!-- Sort by author and then by title -->  
          <CollectionViewSource.SortDescriptions>  
            <scm:SortDescription PropertyName="author"/>  
            <scm:SortDescription PropertyName="title"/>  
          </CollectionViewSource.SortDescriptions>  
          <!-- Group items by author -->  
          <CollectionViewSource.GroupDescriptions>  
            <PropertyGroupDescription PropertyName="author"/>  
            </CollectionViewSource.GroupDescriptions>  
          </CollectionViewSource>  
        <!-- This is the template for each item -->  
        <DataTemplate x:Key="TitleTemplate">  
          <TextBlock FontSize="10" Foreground="#FF333333" Text="{Binding XPath=title}"/>  
        </DataTemplate>  
        <!-- This is the template for the groups -->  
        <DataTemplate x:Key="ListBoxHeader1Style">  
          <Grid Margin="1,6,1,4" >  
            <Grid.RowDefinitions>  
              <RowDefinition Height="Auto"/>  
              <RowDefinition Height="1"/>  
            </Grid.RowDefinitions>  
            <TextBlock Grid.Row="0" FontSize="11" Foreground="#FF333333"   
                       Text="{Binding Path=author}" />  
            <Rectangle SnapsToDevicePixels="True" Grid.Row="1" Stroke="#50000000" Height="1"/>  
          </Grid>  
        </DataTemplate>  
      </ResourceDictionary>  
    </Grid.Resources>  
  
    <ListBox Grid.Row="1" ItemsSource="{Binding Source={StaticResource ItemList}}"   
             ItemTemplate="{StaticResource TitleTemplate}">  
      <ListBox.GroupStyle>  
        <GroupStyle HidesIfEmpty="True" HeaderTemplate="{StaticResource ListBoxHeader1Style}"/>  
      </ListBox.GroupStyle>  
    </ListBox>  
  </Grid>  
</Page>