<Grid>        

        <Button Name="button2" MouseEnter="ColorChangeMouseEvent" MouseLeave="ColorChangeMouseEvent" Margin="198,17,0,0" Height="88" VerticalAlignment="Top" HorizontalAlignment="Left" Width="100">

            <VisualStateManager.VisualStateGroups>

                <VisualStateGroup Name="MouseStates">

                    <VisualState Name="BlueState">

                        <Storyboard>

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

                        </Storyboard>

                    </VisualState>

                    <VisualState Name="OrangeState">

                        <Storyboard>

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

                        </Storyboard>

                    </VisualState>

                </VisualStateGroup>

            </VisualStateManager.VisualStateGroups>

            <Button.Background>

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