New Post: DocumentHeaderTemplate - animation ceases to work when document is undocked

Hello, I have a DocumentHeaderTemplate with animation style to flash the document tab based on the value of a dependency property. This works when the document is docked to the main window however when undocked it does not work. Does anyone have any idea on what I could try to maintain the flashing tab even when the document window is undocked?
The code is below, why doesn't this work?

<ad:DockingManager Grid.Row="1" >
    <ad:DockingManager.DocumentHeaderTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="{Binding Title}">
                    <TextBlock.Style>
                        <Style  TargetType="{x:Type TextBlock}">
                            <Setter Property="Background">
                                <Setter.Value>
                                    <SolidColorBrush Color="Transparent"/>
                                </Setter.Value>
                            </Setter>
                            <Style.Triggers>
                                <DataTrigger Binding="{Binding RelativeSource={RelativeSource AncestorType=Window}, Path=DataContext.HasProblem}" Value="True">
                                    <DataTrigger.EnterActions>
                                        <BeginStoryboard Name="StartBlinking">
                                            <Storyboard>
                                                <ColorAnimation Storyboard.TargetProperty="(Background).(SolidColorBrush.Color)" To="Orange" Duration="00:00:00.4" RepeatBehavior="Forever" AutoReverse="True"/>
                                            </Storyboard>
                                        </BeginStoryboard>
                                    </DataTrigger.EnterActions>
                                </DataTrigger>
                                <DataTrigger Binding="{Binding RelativeSource={RelativeSource AncestorType=Window}, Path=DataContext.HasProblem}" Value="False">
                                    <DataTrigger.EnterActions>
                                        <RemoveStoryboard BeginStoryboardName="StartBlinking"/>
                                    </DataTrigger.EnterActions>
                                </DataTrigger>
                            </Style.Triggers>
                        </Style>
                    </TextBlock.Style>
                </TextBlock>
            </StackPanel>
        </DataTemplate>
    </ad:DockingManager.DocumentHeaderTemplate>
    <ad:LayoutRoot>
        <ad:LayoutPanel Orientation="Horizontal">
            <ad:LayoutDocumentPaneGroup>
                <ad:LayoutDocumentPane>
                    <ad:LayoutDocument Title="Airport Code">
                        <StackPanel>
                            <DataGrid ItemsSource="{Binding View}" />
                        </StackPanel>
                    </ad:LayoutDocument>
                </ad:LayoutDocumentPane>
            </ad:LayoutDocumentPaneGroup>
        </ad:LayoutPanel>
    </ad:LayoutRoot>
</ad:DockingManager>

public partial class Window5 : Window
{

    public AirportCodeDataSource AirportCodeDataSource { get { return this.DataContext as AirportCodeDataSource; } }
    public Window5()
     {
        InitializeComponent();
        this.DataContext = new AirportCodeDataSource();
       this.AirportCodeDataSource.HasProblem = true;
    }

}

public class AirportCode
{

public string Name { get; set; }
public bool Operational { get; set; }

}
public class AirportCodeDataSource : DependencyObject
{

public AirportCodeDataSource()
{
    this.View = new ObservableCollection<AirportCode>
{
    new AirportCode {Name = "JFK", Operational = true},
    new AirportCode {Name = "LHR", Operational = true},
    new AirportCode {Name = "LGW", Operational = true}
};
}

public static readonly DependencyProperty HasProblemProperty =
    DependencyProperty.Register(
    "HasProblem",
    typeof(bool),
    typeof(AirportCodeDataSource));



public bool HasProblem
{
    get { return (bool)GetValue(HasProblemProperty); }
    set { SetValue(HasProblemProperty, value); }
}

public ObservableCollection<AirportCode> View { get; set; }

}