I forgot about highlighting just when u said it's not possible.:-)
Now: 
Regarding a select box - Remember when u type the first letter and then 
the first option that starts with this letter is highlighted? 
I'd like to do that but not for the first letter, but for a string: 
Say I type 4 first chars of a word, then I like the first option starts 
with this string of 4 letters to be highlighted/selected. 

I need to neutrolize something in the select box, in order to select the 
option that fits the first letters that r typed (not just by the first 
letter).
I need to cancel the capture of the first letter.
I.e. - There's a built in function (I guess) that captures the first 
letter u type in a select box, and then select the first option starting 
with that letter.
I can't even capture the letters that are typed, because once the first 
letter is typed, this "built in" function gets into action, and prevent me 
from any other capturing stuff I try. For e.g. - if I try the 
event "onkeyup" in the select, and then in a function, counting the number 
of typed letters (typed by the user), the number I get is the number of 
chars of the content of the option that is immediately selected once 
typing the first letter.
So..does anyone know what's this built-in function name? Moreover, how to 
ignore it?

Thanks