title: Caliburn Micro with TreeView ContextMenu target does not exist
body: <p>It seems (from other posts with similar problems) that I am trying to bind the target to an element which doesn't exist in the same visual tree. I have a ContextMenu on the 3rd level in the TreeView, and am trying to set an action to execute a method on the ViewModel via the Tag of the parent element (TextBlock), but can't get it to work.</p>
  
  <p>The XAML is:</p>
  
  <pre><code>&lt;HierarchicalDataTemplate x:Key="FeatureTemplate"&gt;
      &lt;Grid HorizontalAlignment="Stretch"&gt; 
      &lt;TextBlock Text="{Binding Name}" Tag="{Binding DataContext, RelativeSource={RelativeSource Self}}"&gt;
          &lt;telerik:RadContextMenu.ContextMenu &gt;
          &lt;telerik:RadContextMenu cal:Action.TargetWithoutContext="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}"
           cal:Message.Attach="[Event Opened] = [Action ContextMenuOpened($source)]"&gt;               
          &lt;telerik:RadMenuItem Header="Export" cal:Message.Attach="[Event Click]=[Action ContextMenuClick($source)]"/&gt;
          &lt;/telerik:RadContextMenu&gt;
          &lt;/telerik:RadContextMenu.ContextMenu&gt;
      &lt;/TextBlock&gt;
  &lt;/Grid&gt;
  &lt;/HierarchicalDataTemplate&gt;
  
  &lt;HierarchicalDataTemplate 
  x:Key="FormTemplate" 
  ItemTemplate="{StaticResource FeatureTemplate}" 
  ItemsSource="{Binding List}"&gt;
  &lt;Grid&gt;
      &lt;Grid.ColumnDefinitions&gt;
      &lt;ColumnDefinition Width="Auto"/&gt;
      &lt;ColumnDefinition Width="*"/&gt;
      &lt;/Grid.ColumnDefinitions&gt;
      &lt;Image Source="{Binding Image}" Width="32" Height="32" HorizontalAlignment="Right" Margin="0,3"/&gt;
      &lt;TextBlock Grid.Column="1" Text="{Binding Name}" VerticalAlignment="Center" Margin="5"/&gt;
  &lt;/Grid&gt;
  &lt;/HierarchicalDataTemplate&gt;
  
  &lt;HierarchicalDataTemplate  
      x:Key="JobTemplate"  
  ItemTemplate="{StaticResource FormTemplate}" 
  ItemsSource="{Binding List}"&gt;
  &lt;TextBlock Text="{Binding Name}"/&gt;
  &lt;/HierarchicalDataTemplate&gt;
  
  &lt;telerik:RadTreeView Name="TreeView1" 
   Grid.Row="2" 
   cal:Message.Attach="[Event SelectionChanged] = [Action SetSelectedItem($this.SelectedItem)]" 
   Background="White" 
   ItemsSource="{Binding AvailableData}" 
   ItemTemplate="{StaticResource JobTemplate}" 
   telerik:AnimationManager.IsAnimationEnabled="False" &gt;
  &lt;/telerik:RadTreeView&gt;
  </code></pre>
  
  <p>ViewModel code:
      public void ContextMenuOpened(FrameworkElement source){}</p>
  
  <p>I get the error that ContextMenuOpened target is not found.
  Any help or suggestions would be much appreciated.</p>