Infinitely rotate rectangle in XAML

Something like this

<Rectangle x:Name="rect1" RenderTransformOrigin="0.5, 0.5">
  <Rectangle.RenderTransform>
    <!-- giving the transform a name tells the framework not to freeze it -->
    <RotateTransform x:Name="noFreeze" />
  </Rectangle.RenderTransform>
  <Rectangle.Triggers>
    <EventTrigger RoutedEvent="Loaded">
      <BeginStoryboard>
        <Storyboard>
          <DoubleAnimation
            Storyboard.TargetProperty="(Rectangle.RenderTransform).(RotateTransform.Angle)"
            To="-360" Duration="0:0:1" RepeatBehavior="Forever" />
        </Storyboard>
      </BeginStoryboard>
    </EventTrigger>
  </Rectangle.Triggers>
</Rectangle>

Of course you can remove Loaded trigger and run this storyboard whenever you want.