title: Using a StaticResource inside a ListBox.ItemContainerStyle throws exception
body: <p>The following code throws the exception "System.NullReferenceException was unhandled
    Message=Object reference not set to an instance of an object.
    Source=Wizbang":</p>
  
  <pre><code>&lt;ListBox.ItemContainerStyle&gt;
      &lt;Style TargetType="{x:Type ListBoxItem}"&gt;
          &lt;Style.Resources&gt;
              &lt;SolidColorBrush x:Key="SCB" Color="Orange" /&gt;
          &lt;/Style.Resources&gt;
          &lt;Style.Triggers&gt;
              &lt;Trigger Property="IsSelected" Value="True" &gt;
                  &lt;Setter Property="Background" Value="{StaticResource SCB}" /&gt;
              &lt;/Trigger&gt;
              &lt;Trigger Property="IsMouseOver" Value="True"&gt;
                  &lt;Setter Property="Background" Value="Orange" /&gt;
              &lt;/Trigger&gt;
          &lt;/Style.Triggers&gt;
      &lt;/Style&gt;
  &lt;/ListBox.ItemContainerStyle&gt;
  </code></pre>
  
  <p>However, if I remove the StaticResource reference in the first Trigger's Setter, and replace it with string value, such as, "Orange", like in the second Trigger, everything works fine.</p>
  
  <p>I cannot figure out why.  I use StaticResources similarly in Triggers elsewhere, but it seems that since this is a ListBox.ItemContainerStyle, something works differently.</p>