Hi,
I'm trying to hide collapsible icon of tree, i tried few ways but not working for me , Can any one look in to my code if there is any problem with that

Code:
Ext.onReady(function(){ 
    // shorthand 
    var Tree = Ext.tree; 
    var smartTreeLoader = new Ext.tree.TreeLoader({ 
            dataUrl:'get-nodes-tree.php' 
        }); 
     
    var tree = new Tree.TreePanel({ 
        lines: true, 
        autoScroll:true, 
        border:false, 
        collapsible:true, 
        hideCollapseTool:true, 
        rootVisible: false, 
        loader: smartTreeLoader, 
        root: { 
            expanded: true, 
           
         
            expandable:false, 
            nodeType: 'async', 
            hideCollapseTool:true, 
         
            draggable:false 
             
        } 
    }); 
    var a=new Ext.Panel({ 
        renderTo:'tree-div', 
        items:[tree] 
    }); 
    // render the tree 
    tree.render(); 
    tree.getRootNode().expand(); 
});


php
Code:
[{"text":"Parent1","expanded":true,"collapsible":true,"hideCollapseTool":true,
  "children":[{"id":1,"leaf":true,"text":"Child1","iconCls":"folder"},
             {"id":2,"leaf":true,"text":"Child2","iconCls":"folder"},
             {"id":3,"leaf":true,"text":"Child3","iconCls":"folder"},
             {"id":4,"leaf":true,"text":"Child4","iconCls":"folder"}]},
{"text":"Parent2","expanded":true,
"children":[{"id":5,"leaf":true,"text":"Child1","iconCls":"folder"},
{"id":6,"leaf":true,"text":"Child2","iconCls":"folder"},
{"id":7,"leaf":true,"text":"Child3","iconCls":"folder"},
{"id":8,"leaf":true,"text":"Child4","iconCls":"folder"}]}]