Vertical separator in WPF Ribbon

This is how I would do it.

<ribbon:RibbonGroup.Resources>
    <!-- Vertical Separator-->
    <Style TargetType="{x:Type ribbon:RibbonSeparator}"
           x:Key="KeyRibbonSeparatorVertical">
        <Setter Property="LayoutTransform">
            <Setter.Value>
                <RotateTransform Angle="90"/>
            </Setter.Value>
        </Setter>
    </Style>
</ribbon:RibbonGroup.Resources>

It looks like this doesn't work in the latest version (3.5.40729.1) anymore. The RibbonSeparator also doesn;t work, but you can use:

<Ribbon:RibbonControlGroup Height="55" Margin="5" Width="1" MinHeight="55" MaxWidth="1"/>