Windows phone 8 - Pivot Active, Inactive Header template - xaml

Question

I'd like to use different templates for the header of my pivot, if it's selected/active id like to use template A, if it's inactive/not selected, I'd like to use template B.
What I would like to do is pretty much the same as the facebook app for windows phone, where a small triangle/arrow is displayed on the active pivot. I'm not 100% sure how this is designed, if the icon and arrow is the header template, or if it's just the arrow, or if it's pivot at all...
I would appreciate if someone would shed some light on how this kind of UI can be achieved.

Answer 1

Ended up with a work-around for this
I removed the pivot header entirely and created a stand alone control to navigate the pivot
The nav-viewmodel, shared between the pivot and the Nav control, have a SelectedPage property, which changes when you navigate in the Nav control:
<AppControls:Nav Grid.Row="0"/>
That gives me full control of the layout of the selected menu item.
The SelectedPage property is bound to the pivots selectedindex:
full markup:
<Grid x:Name="LayoutRoot" DataContext="{Binding Nav, Source={StaticResource Locator}}" Background="#E8E8E8">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<!--ContentPanel - place additional content here-->
<AppControls:Nav Grid.Row="0"/>
<phone:Pivot SelectedIndex="{Binding SelectedPage, Mode=TwoWay}" Grid.Row="1" x:Name="MainGui">
<phone:PivotItem x:Name="FrontPage">
<AppControls:Topnav Grid.Row="1" />
</phone:PivotItem>
<phone:PivotItem x:Name="PlacesPage">
<AppControls:PlacesControl Grid.Row="1"/>
</phone:PivotItem>
<phone:PivotItem x:Name="MapPage">
<AppControls:MapControl Grid.Row="1"/>
</phone:PivotItem>
<phone:PivotItem x:Name="SettingsPage">
<AppControls:Settings Grid.Row="1" />
</phone:PivotItem>
</phone:Pivot>
</Grid>