title: How to specify a border for a TreeView inside of a MetroWindow?
body: <p>I just started using the <code>MetroWindow</code> found within the MahApps.Metro package and I noticed that the <code>TreeView</code> in my XAML no longer has a border. I've tried the following but it didn't seem to have any affect:</p>
  
  <pre><code>&lt;TreeView x:Name="AssetsTreeView" 
      ItemsSource="{Binding Assets}"
      Height="250"
      BorderThickness="2"
      BorderBrush="Black"&gt;
      &lt;TreeView.ItemTemplate&gt;
          &lt;HierarchicalDataTemplate ItemsSource="{Binding Items}"&gt;
              &lt;TextBlock Text="{Binding Name}" /&gt;
              &lt;HierarchicalDataTemplate.ItemTemplate&gt;
                  &lt;DataTemplate&gt;
                      &lt;TextBlock Text="{Binding Name}" /&gt;
                  &lt;/DataTemplate&gt;
              &lt;/HierarchicalDataTemplate.ItemTemplate&gt;
          &lt;/HierarchicalDataTemplate&gt;
      &lt;/TreeView.ItemTemplate&gt;
  &lt;/TreeView&gt;
  </code></pre>
  
  <p>In my <code>App.xaml</code> I have the following 4 style pages referenced:</p>
  
  <pre><code>&lt;ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" /&gt;
  &lt;ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Fonts.xaml" /&gt;
  &lt;ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Colors.xaml" /&gt;
  &lt;ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Accents/Blue.xaml" /&gt;
  &lt;ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Accents/BaseLight.xaml" /&gt;
  </code></pre>
  
  <p>I'm guessing the culprit is in one of the styles but I figured I could overwrite it via <code>BorderBrush</code> and <code>BorderThickness</code> on the <code>TreeView</code> element itself (which doesn't seem to be the case). Is there something I'm missing to do this or does this have to be a different way? </p>