<Canvas xmlns="http://schemas.microsoft.com/client/2007" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Canvas.Resources>
    <Storyboard x:Name="circleAnimation">
      <DoubleAnimation Storyboard.TargetName="theCircle"
                       Storyboard.TargetProperty="Opacity"
                       From="1" To="0"
                       Duration="0:0:2"
                       AutoReverse="True" />
    </Storyboard>
  </Canvas.Resources>

  <Ellipse x:Name="theCircle"
           Canvas.Left="50" Canvas.Top="50"
           Width="100" Height="100"
           Fill="Blue" />
  <Rectangle x:Name="theRect"
             Canvas.Left="150" Canvas.Top="150"
             Width="100" Height="100"
             Fill="Red" />
</Canvas>