[flexcoders] Extending TreeItemRenderer

[sarah_e_boys]

I would like to know how I pass a string (topicTitleParameter) in to 
the extended TreeItemRenderer class below. 

package samples
{
        import mx.controls.treeClasses.*;
        import mx.collections.*;
        
        //Item renderer:
        public class MyTreeItemRenderer extends TreeItemRenderer {
                
                public var topicTitle:String;
        
                // Define the constructor.
                public function MyTreeItemRenderer
(topicTitleParameter:String) {
                        super();
                        this.topicTitle = topicTitleParameter;
                }
                
                // Override the set method for the data property
                // to set the font color and style of each node.
                override public function set data(value:Object):void {
                        super.data = value;
                        if(TreeListData(super.listData).label == 
this.topicTitle ) {
                                setStyle("color", 0xff0000);
                                setStyle("fontWeight", 'bold');
                        }
                        else {
                                setStyle("color", 0x000000);
                                setStyle("fontWeight", 'normal');
                        } 
                }
                
                // Override the updateDisplayList() method 
                // to set the text for each tree node. 
                override protected function updateDisplayList
(unscaledWidth:Number,
                unscaledHeight:Number):void {
                        super.updateDisplayList(unscaledWidth, 
unscaledHeight);
                        if(super.data) {
                                if(TreeListData
(super.listData).hasChildren) {
                                        var tmp:XMLList = new XMLList
(TreeListData(super.listData).item);
                                        var myStr:int = tmp
[0].children().length();
                                        super.label.text = 
TreeListData(super.listData).label + "(" + myStr + ")"; 
                                }
                        }
                }
        }
}


I tried the following:
<mx:Tree id="compBalanced" dataProvider="{xlcBalanced}"  
labelFunction="treeLabel"
labelField="@label" width="400" height="500" 
itemRenderer="samples.MyTreeItemRenderer('GridRow')"  />

and get the following error message:
Initializer for 'itemRenderer': cannot parse value of type 
mx.core.IFactory from text 'samples.MyTreeItemRenderer('GridRow')'