title: ComboBox - TreeView, close popup on item select?
body: <p>I have managed to create a ComboBox with treeview as its itempresenter using the <a href="https://stackoverflow.com/questions/1000040/selecteditem-in-a-wpf-treeview">selected item behavior</a>
   here.</p>
  
  <pre><code>&lt;Popup x:Name="PART_Popup" AllowsTransparency="true" Focusable="false" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom"&gt;
      &lt;Microsoft_Windows_Themes:SystemDropShadowChrome x:Name="Shdw" Color="Transparent" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{TemplateBinding ActualWidth}"&gt;
          &lt;Border x:Name="DropDownBorder" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"&gt;
          &lt;ScrollViewer&gt;
              &lt;TreeView  x:Name="PART_TreeView" ItemsSource="{TemplateBinding ItemsSource}"&gt;
                  &lt;Interactivity:Interaction.Behaviors&gt;
                  &lt;ComboTreeView:BindableSelectedItemBehaviour SelectedItem="{Binding RelativeSource={RelativeSource AncestorType={x:Type ComboBox} }, Path=SelectedItem, Mode=TwoWay}" /&gt;    
                  &lt;/Interactivity:Interaction.Behaviors&gt;                                                  
                  &lt;/TreeView&gt;                             
          &lt;/ScrollViewer&gt;
          &lt;/Border&gt;
      &lt;/Microsoft_Windows_Themes:SystemDropShadowChrome&gt;
  &lt;/Popup&gt;
  </code></pre>
  
  <p>Selecting an item in treeview correctly sets the combobox selected item. I am not sure how to close the pop up on selection. Everytime I have to select and click outside the control for the popup to go away. Can this be done in XAML ?</p>