How to make a tree selectednode editable on a button click

[purni]

how to make a tree selectedNode editable on a button click....

initially i tried it using myTree.selectedItem.editable=true;
but this doing somethi..... creating a new node with a leaf node......
i don know why its happening;

Also i did by using a item editor..... but i don know how to integrate
tat on a button click......


here is my code.......

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
layout="absolute">
<mx:XML id="treedata">
<top label="node 0">
<row label="node 1"></row>
<row label="node 3"> </row>
<row label="node 5"></row>
</top>
</mx:XML>

<mx:Tree id="myTree"
width="400" height="400"
editable="true"
itemEditor="Mycomponents.TreeRenderer"
editorHeightOffset="2" editorWidthOffset="-225"
editorXOffset="49" editorYOffset="25"
creationComplete="initCatalog(treedata);"
itemEditBeginning="disableEditing(event);"
itemEditEnd="processData(event);" labelField="@label"/>


<mx:Button x="524" y="120" label="Button" id="btn_add"
click="add_label(value)"/>


<mx:Script>
<![CDATA[
import mx.events.IndexChangedEvent;
import mx.events.ListEvent;
import mx.events.TreeEvent;
//import Tree.TreeRenderer;
import mx.controls.Alert;
import mx.controls.TextInput;
import Mycomponents.TreeRenderer;
//public var set:TreeRenderer;
[Bindable]
public var set_visible:Boolean=false;
public var value:String;

private function add_label(value:String):void
{

// myTree.editedItemRenderer.data.@label=

// nav.editedItemPosition={rowIndex:event.rowIndex}




}

private function initCatalog(cat:Object):void {
myTree.dataProvider = cat;
}

// Define the event listener for the itemEditBeginning event
// to disable editing when the user selects
// the top node in the tree.
private function disableEditing(event:ListEvent):void {
if(event.rowIndex==0) {
event.preventDefault();

}
}

// Define the event listener for the itemEditEnd event
// to copy the updated data back to the data provider
// of the Tree control.
public function processData(event:ListEvent):void {

// Disable copying data back to the control.
event.preventDefault();

// Get new phone number from editor.
myTree.editedItemRenderer.data.@label =

TreeRenderer(event.currentTarget.itemEditorInstance).contactPhone.text;

value=event.toString()
Alert.show(value);

// Get new status from editor.


// Close the cell editor.
// myTree.destroyItemEditor();

// Notify the list control to update its display.
//
myTree.dataProvider.notifyItemUpdate(myTree.editedItemRenderer);
}


]]>
</mx:Script>
<mx:Tree x="460" y="266"></mx:Tree>
</mx:Application>