How to collapse the header panel in DocumentContainer of WPF DockingManager?

<syncfusion:DockingManager x:Name="dockingmanager" UseDocumentContainer="True">
  <ContentControl x:Name="Properties" syncfusion:DockingManager.Header="Properties"/>
  <ContentControl x:Name="Tools" syncfusion:DockingManager.Header="Tools" syncfusion:DockingManager.State="Document"/>
  <ContentControl x:Name="Solution" syncfusion:DockingManager.Header="Solution" syncfusion:DockingManager.State="Document"/>
</syncfusion:DockingManager>

namespace DockingManagerSample
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            (dockingmanager.DocContainer as DocumentContainer).Loaded += 
             MainWindow_Loaded;
        }
        void MainWindow_Loaded(object sender, RoutedEventArgs e)
        {
            HeaderPanel header = VisualUtils.FindDescendant(sender as Visual,       
            typeof(HeaderPanel)) as HeaderPanel;
            header.Visibility = Visibility.Collapsed;
        }
    }
}