How can I listen for mouse wheel events in the Margin between two items in an ItemsControl?

I have an ItemsControl that looks something like this:

<ItemsControl ItemsSource="{Binding}" PreviewMouseWheel="ItemsControl_PreviewMouseWheel" >
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <Grid Margin="0,4"><!--Margin to keep the items from being smashed too closely together-->
                ...
            </Grid>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

The ItemsControl will be one of several items in a scrollable area, but if开发者_StackOverflow社区 I use the mouse wheel over the ItemsControl, nothing happens. So I want to forward the mouse wheel events further up the tree:

private void ItemsControl_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
{
    e.Handled = true;

    RaiseEvent(new MouseWheelEventArgs(e.MouseDevice, e.Timestamp, e.Delta)
    {
        RoutedEvent = UIElement.MouseWheelEvent
    });
}

This mostly works. But when the mouse scrolls over the Margin area (specified by Margin="0,4") between two items in the control, nothing happens. I tried putting the grid inside a decorator, such as a Border, but that doesn't seem to help. How can I capture these mouse wheel events, and forward them up the tree?

The Margin is the area of space left around a Control, and since it's just empty space it doesn't process any events.

An alternative is to either nest controls, such as putting your Grid with the Margin inside a DockPanel without a Margin, or to use a WPF control that has the Padding property such as Border