How to Make ListBox Controls Return to Selected Item On Postback

Windows Server 2008 R2.  IIS 7.  ASP.Net Framework 4.5. 
I have ListBox controls that allow multiple selections on my page.  When the page posts back, the items remain selected (as expected), but the lists return to the top of the list rather than staying at the item(s) I selected.  If the items are down the list (beyond the list height), then I cannot even see that the item(s) were selected.  How can I make the listbox stay at the selected items after postback rather than returning to the top of the list?  ANY help will be appreciated.
P.S.  I was handling this in the past with JavaScript on the aspx page.  But now that I have placed these listbox controls into an Ajax Toolkit tab control, the JavaScript does not work any more.