function forms_update_input_counter(item_id, max_value)
{
  var length = document.getElementById(item_id).value.length;

  document.getElementById(item_id + '_counter').value = max_value - length;
}

function forms_update_checkboxes(form_id, checked)
{
  var elements = document.getElementById(form_id).elements;

  for (var i = 0; i < elements.length; i++) if (elements[i].type == 'checkbox') elements[i].checked = checked;
}