将Silverlight beta 2更新为“TranslatePosition”的最佳方法是什么？

I am upgrading a silverlight beta 2 app to RC0 and have a function that translates a point from a child element to it's parent. The purpose of the function is to ensure that an element appears exactly on top of the child even though they are not on the same canvas and don't share a parent.I am upgrading a silverlight beta 2 app to RC0