title: ListBox is virtual by default?
body: <p>I have a WPF ListBox with some user cards inside.<br>
  When one of those user cards is created (in the ideal case, when the current user receives it's friend list from the network), it makes a network request for a user's information.<br>
  When I scroll in the ListBox , wait a few seconds, and scroll back, the user cards have their default state.<br>
  Upon debugging, I noticed they are unloaded and recreated.  </p>
  
  <p>How can I stop the ListBox from virtualizing the items like this?  </p>
  
  <hr>
  
  <p>Code:  </p>
  
  <pre><code>            &lt;ListBox x:Name="friend_list" Background="{x:Null}" BorderBrush="{x:Null}"&gt;
                  &lt;ListBox.ItemTemplate&gt;
                      &lt;DataTemplate DataType="data:User"&gt;
                          &lt;stuff:UserCard UserID="{Binding Path=UserID}" HorizontalAlignment="Stretch" Margin="0,0,0,0" /&gt;
                      &lt;/DataTemplate&gt;
                  &lt;/ListBox.ItemTemplate&gt;
              &lt;/ListBox&gt;
  </code></pre>