var openImg = new Image();
   openImg.src = "collapse.gif";
   var closedImg = new Image();
   closedImg.src = "expand.gif";
   
function toggleLayer( whichLayer ){  
	var elem, vis;  
	if( document.getElementById )  
	elem = document.getElementById( whichLayer );  
	else if( document.all )
	elem = document.all[whichLayer];  else if( document.layers )
    elem = document.layers[whichLayer];  vis = elem.style;  
    if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)    
    vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';  
    vis.display = (vis.display==''||vis.display=='block')?'none':'block';
    }

function showBranch(branch) {
	      var objBranch = 
	         document.getElementById(branch).style;
	      if(objBranch.display=="block")
	         objBranch.display="none";
	      else
	         objBranch.display="block";
	   }

function swapFolder(img) {
      objImg = document.getElementById(img);
      if(objImg.src.indexOf('expand.gif')>-1)
         objImg.src = openImg.src;
      else
         objImg.src = closedImg.src;
   }