title: WPF ListBox not updating with the ItemsSource
body: <p>I have what I believe should be simple two-way databinding in WPF setup, but the listbox (target) is not updating as the collection changes.</p>
  
  <p>I'm setting this ItemsSource of the ListBox programmatically:  </p>
  
  <pre><code>lstVariable_Selected.ItemsSource = m_VariableList;
  </code></pre>
  
  <p>And the ListBox is declared as follows:  </p>
  
  <pre><code>&lt;ListBox Margin="5" Name="lstVariable_Selected"&gt;
      &lt;ListBox.ItemsPanel&gt;
         &lt;ItemsPanelTemplate&gt;
            &lt;VirtualizingStackPanel Orientation="Horizontal"/&gt;
         &lt;/ItemsPanelTemplate&gt;
      &lt;/ListBox.ItemsPanel&gt;
      &lt;ListBox.ItemTemplate&gt;
         &lt;DataTemplate&gt;
              &lt;Border BorderBrush="Gray" BorderThickness="1" Margin="0"&gt;
                  &lt;TextBlock FontSize="25" Text="{Binding Path=Name}" /&gt;
              &lt;/Border&gt;
         &lt;/DataTemplate&gt;
      &lt;/ListBox.ItemTemplate&gt;
  &lt;/ListBox&gt;
  </code></pre>
  
  <p>When I initially set the ItemsSource, the ListBox (which is not visible at the time) gets its items set.  However, if I go view the ListBox, updates seem to stop at that point.</p>
  
  <p>I can then remove an item from the m_VariableList collection, and it does not disappear from the ListBox.  Likewise, if I add one, it doesn't appear.</p>
  
  <p>What gives?</p>