How to Highlight the items in listbox in javascript?

[bin_bin1]

Hi, there, I would like to know how to Highlight the items in the listbox during onmouseover event. I want it to look the same as the choice list box, in which the mouseover will highlight the item. when I hold on left mouse button and move cursor over list box, the mouseover will highlight the item. How can I do it without holding the left mouse button? Is there a way to do this? Thank you very much. bin