Scrolling a dynamic text box with mousewheel


Can anyone tell me what is the most simple way of using the mousewheel to scroll a large text inserted in a dynamic text box of a Flash MX 2004 movie. I also use to buttons to scroll the text up and down. Here is the code for that (this code in applied to a movie that has a button inside):

onClipEvent ( enterFrame ) {
if (lMouseover) {
_root.texto.scroll += 1;

Thanks for any help