Silverlight animation declaration...

animation.xaml

<Canvas xmlns="..." xmlns:x="..." ...>
<Canvas.Resources>
    <Storyboard
        x:Name="mouseEnterAnimation">
        <ColorAnimation
            Duration="00:00:0.2"
            To="Purple"
            Storyboard.TargetProperty=
        "(Shape.Fill).(GradientBrush.
                GradientStops)[1].
            (GradientStop.Color)" />
        <DoubleAnimation
            Duration="00:00:0.2"
To="0.247" Storyboard.TargetProperty=
        "(Shape.Fill).(GradientBrush.
                GradientStops)[1].
                (GradientStop.Offset)" />
    </Storyboard>
    <Storyboard
        x:Name="mouseLeaveAnimation">
        <ColorAnimation
            Duration="00:00:0.2"
            To="#ffb1b1b1"
            Storyboard.TargetProperty=
        "(Shape.Fill).(GradientBrush.
                GradientStops)[1].
                (GradientStop.Color)" />
        <DoubleAnimation
            Duration="00:00:0.2"
            To="0.494382"
            Storyboard.TargetProperty=
        "(Shape.Fill).(GradientBrush.
                GradientStops)[1].
                (GradientStop.Offset)" />
    </Storyboard>
</Canvas.Resources>