title: How do I hide expander in Hierarchical Data Template when all children are collapsed or hidden?
body: <p>I Have a tree view set up like so:</p>
  
  <pre><code>&lt;TreeView ItemsSource="{Binding TreeRoot}" x:Name="HierarchyTreeView"&gt;
      &lt;TreeView.ItemContainerStyle&gt;
          &lt;Style TargetType="{x:Type TreeViewItem}&gt;
              &lt;Setter Property="Visibility" Value="{Binding IsVisible, Converter={...}}" /&gt;
              ...
          &lt;/Style&gt;
      &lt;/TreeView.ItemContainerStyle&gt;
  
      &lt;TreeView.ItemTemplate&gt;
          &lt;HierarchicalDataTemplate ItemsSource="{Binding Children}"&gt;
              &lt;StackPanel Orientation="Horizontal"&gt;
                  &lt;TextBlock Text="{Binding Name}" ... /&gt;
              &lt;/StackPanel&gt;
          &lt;/HierarchicalDataTemplate&gt;
      &lt;/TreeView.ItemTemplate&gt;
  &lt;/TreeView&gt;
  </code></pre>
  
  <p>Users have the ability to hide items in the treeview. However, when all items' visibility under a node has been set to <code>Collapsed</code> or <code>Hidden</code>, the expander remains.</p>
  
  <p><strong>Is there any way to hide the expander when every child's visibility under an item is set to hidden or collapsed?</strong></p>