Question

I have managed to create a ComboBox with treeview as its itempresenter using the selected item behavior
here.

<Popup x:Name="PART_Popup" AllowsTransparency="true" Focusable="false" IsOpen="{Binding IsDropDownOpen, RelativeSource={RelativeSource TemplatedParent}}" PopupAnimation="{DynamicResource {x:Static SystemParameters.ComboBoxPopupAnimationKey}}" Placement="Bottom">
    <Microsoft_Windows_Themes:SystemDropShadowChrome x:Name="Shdw" Color="Transparent" MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{TemplateBinding ActualWidth}">
        <Border x:Name="DropDownBorder" BorderBrush="{DynamicResource {x:Static SystemColors.WindowFrameBrushKey}}" BorderThickness="1" Background="{DynamicResource {x:Static SystemColors.WindowBrushKey}}">
        <ScrollViewer>
            <TreeView  x:Name="PART_TreeView" ItemsSource="{TemplateBinding ItemsSource}">
                <Interactivity:Interaction.Behaviors>
                <ComboTreeView:BindableSelectedItemBehaviour SelectedItem="{Binding RelativeSource={RelativeSource AncestorType={x:Type ComboBox} }, Path=SelectedItem, Mode=TwoWay}" />    
                </Interactivity:Interaction.Behaviors>                                                  
                </TreeView>                             
        </ScrollViewer>
        </Border>
    </Microsoft_Windows_Themes:SystemDropShadowChrome>
</Popup>

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 ?

Answer 1

In the behavior BindableSelectedItemBehaviour, I added the following logic. I think I’ll move this to a new behavior, but this works.

    private void OnTreeViewSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        this.SelectedItem = e.NewValue;

        var treeView = (TreeView)sender;
        var control = (FrameworkElement)treeView.TemplatedParent;
        ComboBox combo;

        do
        {
            combo = control as ComboBox;

            if (combo != null)
            {
                break;
            }
        }
        while ((control = (FrameworkElement)control.TemplatedParent) != null);

        if (combo == null)
        {
            return;
        }

        Dispatcher.BeginInvoke(new Action(() => combo.IsDropDownOpen = false));
    }