Hello,
Thank you for submitting your query with ComponentArt forum.
I would like to tell you that the behavior which you are observing is working as design. Web.UI Menu's ExpandOnClick behavior is designed to mimic the way menus work in a Windows application i.e. clicking will open a MenuItem, and while a MenuItem is expanded, rolling over any other MenuItem will cause it expand, while collapsing the previously expanded MenuItem. Only clicking away from the Menu or selecting an MenuItem will cause the expanded MenuItem to collapse and reset this behavior.
Hope it helps you.
Thanks.
Harish Malhotra