/// <summary>
/// Header property changed handler
/// </summary>
/// <param name="d">TabItem that changed its Header.</param>
/// <param name="e">DependencyPropertyChangedEventArgs.</param>
private static void OnHeaderChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TabItem ctrl = (TabItem)d;
ctrl.HasHeader = (e.NewValue != null) ? true : false;
ctrl.OnHeaderChanged(e.OldValue, e.NewValue);
}