flex Datagrid checkbox

<?xml version="1.0" encoding="utf-8"?>

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
    xmlns:vo="*"
    layout="horizontal"
    verticalAlign="middle"
    backgroundColor="white"
    creationComplete="init();">

<mx:Script>
  <![CDATA[
   import mx.events.CollectionEvent;
   import mx.utils.ObjectUtil;

   private function init():void {
    arrColl.dispatchEvent(new CollectionEvent(CollectionEvent.COLLECTION_CHANGE));
   }

   private function arrColl_collectionChange(evt:CollectionEvent):void {
    try {
     var tArr:Array = arrColl.source.filter(selectedOnly);
     textArea.text = ObjectUtil.toString(tArr);
     lbl.text = tArr.length.toString() + " item(s) selected";
    } catch (err:Error) {
     // ignore.
    }
   }

   private function selectedOnly(item:ListItemValueObject, idx:uint, arr:Array):Boolean {
    return item.isSelected;
   }
  ]]>
</mx:Script>

<mx:Array />

</mx:Application>

package
{
public class ListItemValueObject
{
  [Bindable]
  public var label:String;

  [Bindable]
  public var isSelected:Boolean;

  public function ListItemValueObject() {
   super();
  }
}
}

<?xml version="1.0" encoding="utf-8"?>

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
    layout="vertical"
    verticalAlign="middle"
    backgroundColor="white">

<mx:Script>
  <![CDATA[
   import mx.controls.dataGridClasses.DataGridColumn;

   private function toggleFilter():void {
    if (checkBox.selected) {
     arrColl.filterFunction = processFilter;
    } else {
     arrColl.filterFunction = null;
    }
    arrColl.refresh();
   }

   private function processFilter(item:Object):Boolean {
    return parseFloat(item.value) == 0;
   }

   private function value_labelFunc(item:Object, col:DataGridColumn):String {
    return item[col.dataField].toFixed(2);
   }
  ]]>
</mx:Script>

<mx:ArrayCollection />
  </mx:ControlBar>
</mx:Panel>

</mx:Application>