ScrollViewr around expanders not scrolling automatically when expander is expanded - silverlight 3

Question

I have several expanders inside a ScrollViewer in a fixed sized ChildWindow. The problem is when each expander expanded,the scroll will not scrolling down automatically and as a result,some of the items in the bottom will get hidden and we have to manually scroll down to see them. I saw some posts like the following link but I guess my situation is different because the children inside expanders will not get focused and I need to do something when the expander is expanded.

http://stackoverflow.com/questions/1225318/how-can-i-make-the-silverlight-scrollviewer-scroll-to-show-a-child-control-with-f

I am just wondering if there is a slution for that- and also would like to know if this problem is solved in silverlight 4.

Thanks in advance for any help.

Sil.