WP: How do I change foreground color of Pivot title to theme color or default color

Question

I want to change Pivot item's title color to match theme color. But I also want to change it back to default color (Black or White depending on background setting in Settings) at some condition. How should I do it. Appreciated!

<phone:PivotItem x:Name="pivot_vip">
<phone:PivotItem.Header>
<TextBlock Text="{Binding Path=LocalizedResources.Artists, Source={StaticResource LocalizedStrings}}"/>
</phone:PivotItem.Header>

private void View_selection_changed(

    ...

    PivotItem currentItem = e.AddedItems[0] as PivotItem;
    if (currentItem != null)
    {
        if (current_view == HanlderType.EVIPHandler)
        {
            (currentItem.Header as TextBlock).Foreground = ??? //Theme color
        }
        else
        {
            (currentItem.Header as TextBlock).Foreground = **???** //whatever default 
        }
    }

Answer 1

Use PhoneForegroundBrush resource key which will be either white or black depending on current system theme.

(currentItem.Header as TextBlock).Foreground = 
           (SolidColorBrush)App.Current.Resources["PhoneForegroundBrush"];