function treeExpand(trname) {
trh = document.getElementById(trname+'_h');
trb = document.getElementById(trname+'_b');

if (trb.style.display == 'none') {
  trh.childNodes[0].innerHTML = "<img src='assets/images/minus.gif'>";
  trb.style.display = 'block';
} else {
  trh.childNodes[0].innerHTML = "<img src='assets/images/plus.gif'>";
  trb.style.display = 'none'; 
}
return true;
}