/*
 * Esto crea un popup en el centro de la pantalla.
 */
function popup(url,width,height) {
	features = 'toolbar=0,location=0,status=0,menubar=0,scrollbars=yes,resizable=0,width='+width+',height='+height;
	win = window.open(url,'',features);
	win.moveTo(((screen.width/2)-(width/2)),((screen.height/2)-(height/2)));
}