<Button Height="23" HorizontalAlignment="Left" Margin="30,0,0,114" Name="button6" VerticalAlignment="Bottom" Width="103" Click="button6_Click">
            <Button.Triggers>
                <EventTrigger  RoutedEvent="Button.MouseEnter">
                    <EventTrigger.Actions>
                        <BeginStoryboard>
                            <Storyboard RepeatBehavior="Forever">
                                <DoubleAnimation Storyboard.TargetName="button6"
                                                 Storyboard.TargetProperty="Button.Height"
                                                 To="33" Duration="0:0:2">
                                </DoubleAnimation>
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger.Actions>
                </EventTrigger>
            </Button.Triggers>
            ButtonDynAddTemplate
        </Button>

Язык XAML
<Rectangle
  Name="Rectangle01"
  Height="100"
  Width="100"
  Fill="{StaticResource MySolidColorBrushResource}">
  <Rectangle.Triggers>
    <EventTrigger RoutedEvent="Rectangle.MouseEnter">
      <BeginStoryboard>
        <Storyboard>
          <ColorAnimation 
            Storyboard.TargetName="Rectangle01"
            Storyboard.TargetProperty="Fill.Color"
            From="Blue" To="AliceBlue" Duration="0:0:1" />
        </Storyboard>
      </BeginStoryboard>
    </EventTrigger>
  </Rectangle.Triggers>
</Rectangle>