How do I (can I?) set the ContextMenu of a AdvancedTabControlItem?

How do I (can I?) set the ContextMenu of a AdvancedTabControlItem?

Following on from my other post I have been looking into being able to right click to bring up a ContextMenu.

Now I can see my ContextMenu is there in Snoop but Right Clicking does not give the expected result? 

I can assign it to the AdvancedTabControl but it then shows the ContextMenu where ever I right click except the tab items!

I am guessing I've missed something obvious here, but looking through the example app I couldn't find anything that would help. The "Custom Context Menu" looked helpfull but using the "MenuOpening" I got a null object...

<UserControl>
    <UserControl.Resources>

        <ContextMenu x:Key="MyContextMenu">
            <MenuItem Command="{Binding RemoveCommand}"
                      CommandParameter="{Binding}"
                      Header="Remove" />
        </ContextMenu>

        <Style TargetType="{x:Type docking:AdvancedTabItem}" x:Key="MyTabStyle">
            <Setter Property="Background" Value="Orange"/>
            <Setter Property="ContextMenu" Value="{StaticResource MyContextMenu}"/>
            <Setter Property="HeaderTemplate">
                <Setter.Value>
                    <DataTemplate >
                        <TextBlock Text="{Binding Name}" FontSize="22" Background="HotPink" />
                    </DataTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </UserControl.Resources>

    <Grid>
        <docking:AdvancedTabControl CanTabsDrag="True" 
                                    ItemContainerStyle="{StaticResource MyTabStyle}" 
                                    ItemsSource="{Binding Groups}" 
                                    SelectedItem="{Binding SelectedGroup}" />
    </Grid>
</UserControl>