<Canvas x:Name="root" 
  xmlns="http://schemas.microsoft.com/client/2007"  
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Width="260" Height="70">

  <Rectangle x:Name="rect4" Canvas.Top="10" Canvas.Left="10" Width="50" Height="50" Fill="#041001">
    <Rectangle.Triggers>
      <EventTrigger  RoutedEvent="Rectangle.Loaded" >
       <BeginStoryboard>
        <Storyboard x:Name="sb_4" 
          Storyboard.TargetName="rect4"
          Storyboard.TargetProperty="(Canvas.Left)"
          Duration="0:0:0"
	  RepeatBehavior="2.5x"
        >
          <DoubleAnimation x:Name="anim_4" 
            BeginTime="0:0:1"
            FillBehavior="Stop"
            From="100" To="200" 
          />
        </Storyboard>
       </BeginStoryboard>
     </EventTrigger>
    </Rectangle.Triggers>
  </Rectangle>

</Canvas>

