Interferes with pages with DrawingSurfaceBackgroundGrid

[dancrevier]

I ran into a problem where a page with a DrawingSurfaceBackgroundGrid would start getting an InvalidOperationException saying it's not the first element when the theme is swapped. It was also reported here: http://social.msdn.microsoft.com/Forums/en-US/wpdevelop/thread/4e4550a0-29df-4bd2-8589-2eb65fb6eb1c

[jeffwilcox]

Thanks - I'm not resourced to fix this right now, but am happy to take contributions or learn more about the issue if you have more data to share. Thx!