I'm trying to get an ItemsPanelTemplate working for a ListBox. The ListBox is used in a DataTemplate, and none of my implicit ListBox styles override the default visual style. For some reason, the ItemsPanelTemplate I'm specifiying for the control (a WrapPanel) is being ignored and a StackPanel is used instead.
This is the entire template, I can only assume there's something I'm missing which is causing this.
<DataTemplate x:Key="GroupLargeIconsTemplate" DataType="{x:Type Core:IGroup}">
<ListBox ItemsSource="{Binding Children}" OverridesDefaultStyle="True">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel HorizontalAlignment="Left" VerticalAlignment="Top" IsItemsHost="True" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollBarVisibility="Auto"
Width="{Binding (FrameworkElement.ActualWidth), RelativeSource={RelativeSource AncestorType=ScrollContentPresenter}}" />
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<DataTemplate.Resources>
<conv:IconConverter x:Key="IconConverter"/>
</DataTemplate.Resources>
<StackPanel Margin="2" Width="100" Height="140">
<Image Source="{Binding Icon,Converter={StaticResource IconConverter},ConverterParameter=96}"/>
<TextBlock Text="{Binding Name}" TextWrapping="Wrap" TextTrimming="CharacterEllipsis" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</DataTemplate>