Text hilite rollover in text field

[RGould8 at aol.com]

If I want to have a text field with a list of items, and have rollovers 
working over that text field so that moving the mouse up and down automatically 
hilites the line underneath the mouse, what's the best way to accomplish this?

I've tried playing with the mouseWithin, hilitedLine, and hilite commands, 
but can't seem to piece them together in a way that works.   

something like:

on MouseWithin
       set the hilitedLine of field "popuptext" to (the mouseLine)
end MouseWithin