title: How to bind collection in collection to context menu and take contextmenu item through click
body: <p>I try to bind <code>itemssource</code> (collection in collection) to context menu and i want to take a context menu item through click <strong>(MVVM)Caliburn</strong></p>
  
  <pre><code>&lt;TreeView x:Name="TreeViewName"  BorderThickness="0" ItemsSource="{Binding RegionsTree}"&gt;
              &lt;TreeView.ItemTemplate&gt;
                  &lt;HierarchicalDataTemplate ItemsSource="{Binding Children}"&gt;
                      &lt;RadioButton Tag="{Binding DataContext, ElementName=TreeViewName}" Content="{Binding Name}" 
                                   cal:Message.Attach="[Click]=[ShowItemScreen($dataContext)];[PreviewMouseRightButtonDown]=[Action OnContextMenuOpening($source)]"
                                   GroupName="TestTree"&gt;
                          &lt;RadioButton.ContextMenu&gt;
                              &lt;ContextMenu   ItemsSource="{Binding RegionCategories}" cal:Action.TargetWithoutContext="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}"&gt;
                                  &lt;ContextMenu.ItemContainerStyle&gt;
                                      &lt;Style TargetType="MenuItem"&gt;
                                          &lt;Setter Property="MenuItem.Header" Value="{Binding Name}" /&gt;
                                          &lt;Setter Property="MenuItem.ItemsSource" Value="{Binding Commands}" /&gt;
                                          &lt;Setter Property="cal:Message.Attach" Value="[Action ContextMenuItemClick($eventArgs)]"/&gt;
                                      &lt;/Style&gt;
                                  &lt;/ContextMenu.ItemContainerStyle&gt;
                              &lt;/ContextMenu&gt;
                          &lt;/RadioButton.ContextMenu&gt;
                      &lt;/RadioButton&gt;
                  &lt;/HierarchicalDataTemplate&gt;
              &lt;/TreeView.ItemTemplate&gt;
              &lt;TreeView.ItemContainerStyle &gt;
                  &lt;Style TargetType="{x:Type TreeViewItem}"&gt;
                      &lt;Setter Property="IsExpanded" Value="True"/&gt;
                  &lt;/Style&gt;
              &lt;/TreeView.ItemContainerStyle&gt;
          &lt;/TreeView&gt;
  </code></pre>