Silverlight. Cannot find VisualTreeHelper GetDescendantBounds

Cannot fi开发者_StackOverflow中文版nd method in silverlight VisualTreeHelper.GetDescendantBounds(item). Do you know any analogs?

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There is no GetDescendantBounds in silverlight. But Charles Petzold posted analog here:

http://www.charlespetzold.com/blog/2008/11/250534.html