我们如何以编程方式更改silverlight控件的zindex？

    <Rectangle x:Name="Rectangle1" Width="100" Height="100" Fill="Red" Canvas.Left="50" Canvas.Top="50"/>
    <Rectangle x:Name="Rectangle2" Width="100" Height="100" Fill="Blue" Canvas.Left="75" Canvas.Top="75"/>
</Canvas>

public void ChangeZIndex(UIElement element, int newZIndex)
{
    Canvas.SetZIndex(element, newZIndex);
}

ChangeZIndex(Rectangle1, 1);
ChangeZIndex(Rectangle2, 2);