HI,

Wire up the client-side NodeExpanded event.

Here is javascript code  that will allow only one nodeset to be expanded at a time.

 function UltraWebTree1_NodeExpand(treeId, nodeId){
 //Add code to handle your event here.
 // debugger;
 var node = igtree_getNodeById(nodeId);
 var tree = igtree_getTreeById(treeId);
 var level = node.getLevel();
 if (level == 0)
 {
    
     var nodes =  tree.getNodes();
     for (var i = 0; i < nodes.length; i++)
     {
       if (nodes.Id != nodeId)
       nodes.setExpanded(false);
     }
 }
 
 
// node.setExpanded(true);