Win8 画刷

<StackPanel>
            <Button Content="点我" FontSize="30" >
                <Button.Background>
                    <SolidColorBrush Color="Red"/>
                </Button.Background>
            </Button>
            <Button Content="线性画刷" HorizontalAlignment="Left" Margin="14,448,0,0" VerticalAlignment="Top" Width="650" Height="87">
                <Button.Background>
                    <LinearGradientBrush>
                        <GradientStop Color="Red" Offset="0.1"/>
                        <!--<GradientStop Color="blue" Offset="0.1"/>-->
                        <GradientStop Color="Blue" Offset="0.5"/>
                        <!--<GradientStop Color="Black" Offset="0.5"/>-->
                        <GradientStop Color="Black" Offset="1"/>
                    </LinearGradientBrush>
                </Button.Background>
            </Button>
            <TextBlock HorizontalAlignment="Left" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top"/>
            <TextBlock Text="我是一只小小鸟，想要飞，可惜翅膀断了" FontSize="30" >
                <TextBlock.Foreground>
                    <LinearGradientBrush>
                        <GradientStop x:Name="gs1" Color="Yellow" Offset="0.1"/>
                        <GradientStop x:Name="gs2" Color="Blue" Offset="0.1"/>
                        <GradientStop Color="Blue" Offset="1"/>
                    </LinearGradientBrush>
                </TextBlock.Foreground>
            </TextBlock>
        </StackPanel>

后台------------
protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            DispatcherTimer timer = new DispatcherTimer();
            timer.Interval = TimeSpan.FromMilliseconds(700);
            timer.Tick += timer_Tick;
            timer.Start();
        }

        void timer_Tick(object sender, object e)
        {
            gs1.Offset += 0.01;
            gs2.Offset += 0.01;
        }