Selecting all items on a dataGroup

[scott matheson]

Hi
    i want to selecta ll the items in a dataGrid, i was trying to populate the 
selectedItems,  any ideas 

thanks 



private function selectAll():void{

    dg.selectedItems = null;

   var _user;
   for each( _user in this._listofUser){
        dg.selectedItems.push(_user);
   }

}



<s:DataGrid id="dg"  width="300" height="500" dataProvider="{this._listofUser}"
         selectionMode="multipleRows"

   <s:columns>
      <s:ArrayCollection>

         <s:GridColumn headerText="First" dataField="firstName" minWidth="50"  
/>
         <s:GridColumn headerText="Surname" dataField="surname"  minWidth="70"  
/>


      </s:ArrayCollection>
   </s:columns>


</s:DataGrid>