How to change menu control pop-up behaveior?

[wenyangcheng]

Hi, I successfully create a asp.net menu control with parent nodes and children nodes(Yeah~I am new to .net). However, my boss wants it to be in certain ways (so picky). When user uses keyboard to tab through the parent nodes, he wants the child menu pop-up instead of using left right keys. I don't know if there is anyway to modify the JavaScript behavior on the menu control or there is a property I overlooked. Somebody please give me a light! Thanks a million.