Auto complete customization?

Using Rails built-in auto-complete text field helper, when the
autocomplete menu shows up, the first option in it starts out
‘selected’. Meaning if the user hits ‘return’, it will put that selected
item into the text box.

I want the auto complete menu to show up under the text field, but I
don’t want any of the items to be ‘selected’ until the user clicks on
one or presses the down arrow. Even after the autocomplete shows up, I
want a return to submit the form, as per usual.

Is there any not too hard way to do this anyone can help me with,
without abandoning the auto-complete helper entirely?