Cannot restore hidden window

I try to load the saved layout

    public partial class MainWindow : Window
    {
        private string m_layout = @"<DockSiteLayout xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema"" SerializationFormat=""All"">
	<AutoHideHost />
	<Content xsi:type=""Workspace"" AutoHideSize=""274,232"" DockedSize=""274,232"" DocumentSize=""274,232"" FloatingSize=""274,232"" Size=""274,232"">
		<Content xsi:type=""TabbedMdiHost"">
			<Content xsi:type=""SplitContainer"" AutoHideSize=""274,232"" DockedSize=""274,232"" DocumentSize=""274,232"" FloatingSize=""274,232"" Size=""274,232"" Orientation=""Horizontal"">
				<UIElement xsi:type=""TabbedMdiContainer"" AutoHideSize=""134.5,232"" DockedSize=""134.5,232"" DocumentSize=""134.5,232"" FloatingSize=""134.5,232"" Size=""134.5,232"" SelectedWindowUniqueId=""45b992b9-0190-4585-b2dc-600c01ad2a70"">
					<UIElement xsi:type=""DocumentWindowRef"" UniqueId=""45b992b9-0190-4585-b2dc-600c01ad2a70"" />
				</UIElement>
			</Content>
		</Content>
	</Content>
	<DocumentWindows>
		<DocumentWindow UniqueId=""45b992b9-0190-4585-b2dc-600c01ad2a70"" AutoHideSize=""134.5,232"" DockedSize=""134.5,232"" DocumentSize=""134.5,232"" FloatingSize=""134.5,232"" Size=""134.5,232"" IsOpen=""false"" LastState=""Document"" Name=""Editor"" StandardMdiBounds=""0,0,300,200"" State=""Document"" />
	</DocumentWindows>
</DockSiteLayout>";

        public MainWindow()
        {
            InitializeComponent();
            Load();
        }

        void Load()
        {
            var serializer = new DockSiteLayoutSerializer
            {
                SerializationBehavior = DockSiteSerializationBehavior.All,
                DocumentWindowDeserializationBehavior = DockingWindowDeserializationBehavior.AutoCreate,
            };
            serializer.DockingWindowDeserializing += SerializerOnDockingWindowDeserializing;
            try
            {
                serializer.LoadFromString(m_layout, root);
            }
            catch (Exception ex)
            {

                throw;
            }
        }

        private void SerializerOnDockingWindowDeserializing(object sender, DockingWindowDeserializingEventArgs e)
        {
            e.Window.Header = "window1";
        }
    }

 and

<Window x:Class="TestLoad.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:docking="http://schemas.actiprosoftware.com/winfx/xaml/docking"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <docking:DockSite x:Name="root">
            <docking:Workspace >
                <docking:TabbedMdiHost>
                    <docking:TabbedMdiContainer>
                    </docking:TabbedMdiContainer>
                </docking:TabbedMdiHost>
            </docking:Workspace>
        </docking:DockSite>
    </Grid>
</Window>

 I want to save the hidden status of restored window (IsOpen=false) but the serializer always oopens windows. How can I restore the saved IsOpen status?

Furthermore I want to use MVVM template in the application. Can I manage the IsOpen property from my viewmodel?

Now if I add

<Setter Property="IsOpen" Value="{Binding IsVisible, Mode=TwoWay}" />

 to the DocumentWindow style then the exception throws

"This operation is invalid since the DockingWindow has not yet been registered with a DockSite."