function handleEnter (field, event) {
  var keyCode = event.keyCode ? event.keyCode : 
                event.which ? event.which : event.charCode;
  if (keyCode == 13) {
    var i;
    for (i = 0; i < field.form.elements.length; i++)
      if (field == field.form.elements[i])
        break;
    i = (i + 1) % field.form.elements.length;
    field.form.elements[i].focus();
    return false;
  }
  else
    return true;
}