<UserControl x:Class="AnimationSample.Page"

    xmlns="http://schemas.microsoft.com/client/2007" 

    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 

    Width="300" Height="150">

  <Grid x:Name="LayoutRoot" Background="White">

    <Grid.Triggers>

      <EventTrigger RoutedEvent="Grid.Loaded">

        <EventTrigger.Actions>

          <BeginStoryboard>

            <Storyboard x:Name="CrawlingBorder" RepeatBehavior="Forever">

              <DoubleAnimationUsingKeyFrames Storyboard.TargetName="rectangle" 

                Storyboard.TargetProperty="(Shape.StrokeDashOffset)" BeginTime="00:00:00">

                <SplineDoubleKeyFrame KeyTime="00:00:00" Value="0" />

                <SplineDoubleKeyFrame KeyTime="00:00:00.5000000" Value="5" />

              </DoubleAnimationUsingKeyFrames>

            </Storyboard>

          </BeginStoryboard>

        </EventTrigger.Actions>

      </EventTrigger>

    </Grid.Triggers>

    <Rectangle Stroke="Green" StrokeThickness="6" StrokeDashArray="3,2" StrokeDashCap="Round" 

               Margin="20" StrokeDashOffset="0" StrokeLineJoin="Round" x:Name="rectangle">

    </Rectangle>

    <TextBlock FontFamily="Lucida Sans Unicode" FontSize="24" 

               Text="Crawling Border" FontWeight="Bold" 

               HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="#FFDE680A"/>

  </Grid>

</UserControl>