function f_in_el (el) {
  var nodes = new Array();
  
  if (el && el.getElementsByTagName) {
    $A(el.getElementsByTagName("*")).each( function (node) {
      if (node.nodeType == 1 && 
          (node.tagName == 'INPUT' || 
           node.tagName == 'SELECT' ||
           node.tagName == 'TEXTAREA')) {
        nodes.push(node);
      }
    });
  }
  
  return nodes;
}

function set_disabled_in_el(el, disabled) {
  f_in_el(el).each( function (node) {
    node.disabled = disabled ? true : false;
  })
}