I have a UserControl with a templated grouped listbox with expanders and only want one expander open at any time. I have browsed through the site but haven't found anything except binding the IsExpanded to IsSelected which isn't quite what I want.

I am trying to put some code in the Expanded event that would loop through Expanders and close all the ones that aren't the expander passed in the Expanded event. I can't seem to figure out how to get at them. I've tried ListBox.Items.Groups but didn't see how to get at them and tried ListBox.ItemContainerGenerator.ContainerFromItem (or Index) but nothing came back.

Thanks

<ListBox Name="ListBox">
<ListBox.GroupStyle >
<GroupStyle>
<GroupStyle.ContainerStyle>
<Style TargetType="{x:Type GroupItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type GroupItem}">
<Border BorderBrush="CadetBlue" BorderThickness="1">
<Expander BorderThickness="0,0,0,1" Expanded="Expander_Expanded"
Focusable="False"
IsExpanded="{Binding IsSelected,
RelativeSource={RelativeSource FindAncestor, AncestorType= {x:Type ListBoxItem}}}" >
<Expander.Header>
<Grid>
<StackPanel Height="30" Orientation="Horizontal">
<TextBlock Foreground="Navy" FontWeight="Bold"
Text="{Binding Path=Name}" Margin="5,0,0,0"
MinWidth="200" Padding="3"
VerticalAlignment="Center" />
<TextBlock Foreground="Navy" FontWeight="Bold"
Text=" Setups: " VerticalAlignment="Center" HorizontalAlignment="Right"/> <TextBlock Foreground="Navy" FontWeight="Bold" Text="{Binding Path=ItemCount}" VerticalAlignment="Center" HorizontalAlignment="Right" />
</StackPanel>
</Grid>
</Expander.Header>
<Expander.Content>
<Grid Background="white" > <ItemsPresenter />
</Grid>
</Expander.Content>
<Expander.Style >
<Style TargetType="{x:Type Expander}">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="true">
<Setter Property="Background">
<Setter.Value>
<LinearGradientBrush StartPoint="0,0" EndPoint="0,1">
<GradientStop Color="WhiteSmoke" Offset="0.0" /> <GradientStop Color="Orange" Offset="1.0" /> </LinearGradientBrush> </Setter.Value> </Setter> </Trigger> <Trigger Property="IsMouseOver" Value="false" <Setter Property="Background"> <Setter.Value>
</code>