[flexcoders] AdvancedDataGrid ItemRenderer

[securenetfreedom]

I am using an ADG with HierarchicalData to group my data. I am using a
checkbox item renderer that the user can check to archive the row.
However, the checkbox is diplaying on every row and I need it to
display only on the sub-set like below:

Group | Archive | Title  |
Group1
------|-- chk --| Trains |
------|-- chk --| Planes |
Group2
------|-- chk --| Autos  |

I have tried setting the visibility of the Canvas (the base of the 
checkbox itemrenderer component) in the creationComplete handler and
in the 'set data' method of the component which works on the first
pass, but when scrolling the grid or expanding the nodes, results are
inconsistent. 

private var _vis:Boolean;
            // called by creationComplete event
            public function init():void{
                var nodeName:String = _listData["item"].name();
                _vis = (nodeName == "item");                    
                this.visible = _vis;            
            }
override public function set data(value:Object):void {
                super.data = value;                
                chkbox.selected = (value[_dataField] == "true");
                this.visible = _vis;
            }

Thanks for your input. 

Jeff