function ajax_loading_start(idElement) {
  var str = '<img src="../images/loading.gif" />';
  var el = $(idElement);
  if(el!=null) {                                    
    el.innerHTML = str;
  }
}

function ajax_loading_stop(idElement) {
  var el = $(idElement);
  if(el!=null) {
    el.innerHTML = '';
  }
}