Длина строки...

[Nirth]

//eta tipa strochka
var myStr:String = "gfhgfsjdfh fddhjfdj dfshgdjfhjds";

/*
tut nam dolzno bit kakim nit sposobom izvestna chirina knopki(mozhno skazem zadavat shirinu bukvi cherez CSS i ottuda ze ee i brat)
*/
var shirina:Number = 4//ya napisal tak u teba mozet bit cherez css po drugomu;

//funciya
function getShirina (shirina) {
var num:Number = this.myStr.lenght;
var otvet:Number = this.num*this.shirina;
return otvet;
}