Анимация и метод Storyboard.GetCurrentState()

<Window x:Class="WpfAnimation.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfAnimation"
        mc:Ignorable="d"
        Title="MainWindow" Height="286" Width="484">
    <Window.Resources>
        <Style x:Key="ToVerdana">
            <Style.Triggers>
                <DataTrigger Binding="{Binding ElementName=TextBox, Path=IsMouseOver}" Value="True" >
                    <Setter Property="Button.FontFamily" Value="Verdana"/>
                </DataTrigger>
            </Style.Triggers>
        </Style>
        <Storyboard x:Key="Blink">
            <DoubleAnimation Storyboard.TargetName="Ellipse"
                             Storyboard.TargetProperty="Opacity" 
                             From="1" To="0" Duration="0:0:0.3"
                             AutoReverse="True" RepeatBehavior="Forever"/>        </Storyboard>
 
    </Window.Resources>
    <Grid x:Name="MainGrid" ShowGridLines="True">
        <Button x:Name="BlinkButton" Content="Blink Ellipse" HorizontalAlignment="Left" Margin="10,10,10,183"  Width="122" Height="40" Click="BlinkButton_Click"/>
        <Ellipse x:Name="Ellipse" Fill="Red" HorizontalAlignment="Left" VerticalAlignment="Bottom" Width="129" Height="111" MouseDown="Ellipse_MouseDown"/>
        <TextBox x:Name="TextBox" HorizontalAlignment="Left" Height="236" Margin="190,10,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="276"/>
    </Grid>
</Window>

namespace WpfAnimation
{
    public partial class MainWindow : Window
    {
        Storyboard sb;
 
        public MainWindow()
        {
            InitializeComponent();
            sb = (Storyboard)this.FindResource("Blink");
            //sb.Begin(); sb.Stop();
        }
 
        public void UpdateState()
        {
            TextBox.Text += sb.GetCurrentState().ToString();
        }
 
        private void BlinkButton_Click(object sender, RoutedEventArgs e)
        {
            if (sb.GetCurrentState() != ClockState.Active) { sb.Begin(); UpdateState(); }
            else { sb.Stop(); UpdateState(); }
        }
 
        private void Ellipse_MouseDown(object sender, MouseButtonEventArgs e)
        {
            UpdateState();
        }
    }
}