Silverlight Panels

I currently have two panels with controls on my page and when i set the top to hidden and bottom panel to visible the bottom panel is hovering down the middle of the page.

Is there a way to set this / use another开发者_如何学JAVA control so that the 2nd panel will go to the top of the page.

thanks

<StackPanel>
    <local:MyPanel1 Width="300" Height="100" Visibility="Collapsed" />
    <local:MyPanel2 Width="300" Height="100" />
</StackPanel>

You can set the panels' visibility in codebehind, or better, databind it to your ViewModel (possibly using a ValueConverter to convert to the Visibility enum).