//para controlar laa opciónes de menú
var vacio = new Image();
vacio.src = "img/trans.gif";
var flecha = new Image();
flecha.src = "img/ico_triangulillo.gif";

function mOvr(num){ 
    var img = document.getElementById("m_"+num);
    img.src = flecha.src;
}
function mOut(num){ 
    var img = document.getElementById("m_"+num);
    img.src = vacio.src;
}