Selecting a ListBoxItem when its inner ComboBox is focused - wpf

Question

I have a DataTemplate that will be a templated ListBoxItem, this DataTemplate has a
ComboBox in it which when it has focus I want the ListBoxItem that this template
represents to become selected, this looks right to me. but sadly enough it doesn't work =(
So the real question here is within a DataTemplate is it possible to get or set the value
of the ListBoxItem.IsSelected property via a DataTemplate.Trigger?
<DataTemplate x:Key="myDataTemplate"
DataType="{x:Type local:myTemplateItem}">
<Grid x:Name="_LayoutRoot">
<ComboBox x:Name="testComboBox" />
</Grid>
<DataTemplate.Triggers>
<Trigger Property="IsFocused" value="true" SourceName="testComboBox">
<Setter Property="ListBoxItem.IsSelected" Value="true" />
</Trigger>
</DataTemplate.Triggers>
</DataTemplate>
<ListBox ItemTemplate="{StaticResource myDataTemplate}" />

Answer 1

I found a solution for your problem.
The problem is that when you have a control on your listboxitem, and the control is clicked (like for inputting text or changing the value of a combobox), the ListBoxItem does not get selected.
this should do the job:
public class FocusableListBox : ListBox
{
protected override bool IsItemItsOwnContainerOverride(object item)
{
return (item is FocusableListBoxItem);
}
protected override System.Windows.DependencyObject GetContainerForItemOverride()
{
return new FocusableListBoxItem();
}
}
--> Use this FocusableListBox in stead of the default ListBox of WPF.
And use this ListBoxItem:
public class FocusableListBoxItem : ListBoxItem
{
public FocusableListBoxItem()
{
GotFocus += new RoutedEventHandler(FocusableListBoxItem_GotFocus);
}
void FocusableListBoxItem_GotFocus(object sender, RoutedEventArgs e)
{
object obj = ParentListBox.ItemContainerGenerator.ItemFromContainer(this);
ParentListBox.SelectedItem = obj;
}
private ListBox ParentListBox
{
get
{
return (ItemsControl.ItemsControlFromItemContainer(this) as ListBox);
}
}
}
A Treeview does also have this problem, but this solution does not work for a Treeview, 'cause SelectedItem of Treeview is readonly.
So if you can help me out with the Treeview please ;-)

Answer 2

I found that I preferred to use this:
<Style TargetType="ListBoxItem">
<Style.Triggers>
<Trigger Property="IsKeyboardFocusWithin" Value="True">
<Setter Property="IsSelected" Value="True"></Setter>
</Trigger>
</Style.Triggers>
</Style>
Simple and works for all the listboxitems, regardless of what's inside.

Answer 3

No idea why your trigger don't work. To catch the get focus event of the combo box (or any control inside a listbox item) you can use attached routed events. You could put the code also in a derived listbox if you need this behavior in other parts of your application.
XAML:
<Window x:Class="RoutedEventDemo.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Specialized="clr-namespace:System.Collections.Specialized;assembly=System"
xmlns:System="clr-namespace:System;assembly=mscorlib"
Height="300" Width="300">
<Window.Resources>
<DataTemplate x:Key="myDataTemplate">
<Grid>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding}" Margin="5,0"/>
<ComboBox Width="50">
<ComboBoxItem>AAA</ComboBoxItem>
<ComboBoxItem>BBB</ComboBoxItem>
</ComboBox>
</StackPanel>
</Grid>
</DataTemplate>
</Window.Resources>
<Grid>
<ListBox ItemTemplate="{StaticResource myDataTemplate}">
<ListBox.ItemsSource>
<Specialized:StringCollection>
<System:String>Item 1</System:String>
<System:String>Item 2</System:String>
<System:String>Item 3</System:String>
</Specialized:StringCollection>
</ListBox.ItemsSource>
</ListBox>
</Grid>
</Window>
Code behind hooking up to all got focus events.
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace RoutedEventDemo
{
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
EventManager.RegisterClassHandler(typeof(UIElement),
GotFocusEvent,
new RoutedEventHandler(OnGotFocus));
}
private static void OnGotFocus(object sender, RoutedEventArgs e)
{
// Check if element that got focus is contained by a listboxitem and
// in that case selected the listboxitem.
DependencyObject parent = e.OriginalSource as DependencyObject;
while (parent != null)
{
ListBoxItem clickedOnItem = parent as ListBoxItem;
if (clickedOnItem != null)
{
clickedOnItem.IsSelected = true;
return;
}
parent = VisualTreeHelper.GetParent(parent);
}
}
}
}