var ie=document.all ? 1 : 0;
var ns6=document.getElementById&&!document.all ? 1 : 0;
var opera=window.opera ? 1 : 0;



function openFolder(childObj, parentObj){
  var child="";
  var parent="";
  var sw="img/sidenav_minus.gif";
  var hd="img/sidenav_plus.gif";
  if(ie || ns6 || opera){
    child=ns6 ? document.getElementById(childObj).style : document.all(childObj).style;
    parent=ns6 ? document.getElementById(parentObj) : document.all(parentObj);
    if (child.display=="none"){
      child.display="block";
      parent.src=sw;
    }else{
      child.display="none";
      parent.src=hd;
    }
  }
}