<Grid>

    <Rectangle Name="Rectangle1" MouseEnter="ColorChangeMouseEvent" Margin="198,17,0,0" Height="88" 

VerticalAlignment="Top" HorizontalAlignment="Left" Width="100">

        <VisualStateManager.VisualStateGroups>

            <VisualStateGroup Name="MouseStates">

                    <VisualState Name="BlueState" />

                <VisualStateGroup.Transitions>

                        <VisualTransition To="BlueState" GeneratedDuration="0:0:2">

                            <VisualTransition.Storyboard>

                                <Storyboard>

                                    <ColorAnimation To="Blue" Storyboard.TargetName="rectBrush" Storyboard.TargetProperty="Color"/>

                                </Storyboard>

                            </VisualTransition.Storyboard>

                        </VisualTransition>                       

                    </VisualStateGroup.Transitions>

            </VisualStateGroup>

        </VisualStateManager.VisualStateGroups>

        <Rectangle.Fill>

            <SolidColorBrush x:Name="rectBrush" Color="Orange"/>