This is a copy from my reply to the support ticket:
I'm afraid I
might have not understood your question properly, but I believe you
face a problem with the animation of the expanded menu item. Please,
find attached a small page, demonstrating how you can initially disable
the animation and expand the item. After the expand the animation is
Would you please, complete the page to demonstrate your exact problem if I am missing something?
If there is no problem to continue the discussion in the forums, please, post here, so that other visitors benefit the discussion.
the Telerik team