Can a ToolWindowContainer (with AutoHide) have a scroll bar if the tabs overflow?

If I add lots of the ToolWindows to the ToolWindowContainer then I do not see a scroll bar appear for the tabs using the following xaml. I can right click and see the menu with all of the tabs in it, even though I am not using TabOverflowBehavior=ScrollWithMenu.

Is it possible to have a scroll bar for tab overflow in this situation?

I have the following xaml

<Grid>
<docking:DockSite Name="DockSite" >
<docking:DockSite.AutoHideLeftContainers>
<docking:ToolWindowContainer HasCloseButton="False" TabOverflowBehavior="Scroll" >
<docking:ToolWindow Title="Targets" TabTintColor="Green">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="Targets" TabTintColor="Red">

</docking:ToolWindow>
<docking:ToolWindow Title="+">

</docking:ToolWindow>
</docking:ToolWindowContainer>
</docking:DockSite.AutoHideLeftContainers>
<docking:Workspace>
<docking:StandardMdiHost>
<docking:DocumentWindow x:Name="documentWindow1" CanStandardMdiMaximize="False" CanStandardMdiMinimize="False" StandardMdiWindowState="Maximized" CanFloat="False" CanDragToLinkedDockSites="False" CanDragTab="False" CanDock="False" CanClose="False" CanAttach="False" >

</docking:DocumentWindow>
</docking:StandardMdiHost>
</docking:Workspace>
</docking:DockSite>

</Grid>