      *  Creates a clip mask with the specified dimensions.
      */
     mx_internal function createItemMask(x:Number, y:Number,
-                                    width:Number, height:Number):DisplayObject
+                width:Number, height:Number, contentHolder:DisplayObjectContainer = null):DisplayObject
     {
         var mask:Shape;
 

            e.addResponder(new ItemResponder(selectionDataPendingResultHandler, selectionDataPendingFailureHandler,
                                                    new ListBaseSelectionDataPending(useFind, 0, items, null, 0)));
            return;
        }

        setSelectionDataLoop(items, 0, useFind);

     */
    private var lastHighlightItemIndices:Point;

    /**
     *  Temporary array to manage order of selectedItems
     */
    private var selectionDataArray:Array;

    mx_internal var dragScrollingInterval:int = 0;

    /**
     *  @private
     *  An Array of Shapes that are used as clip masks for the list items
     */
    mx_internal var itemMaskFreeList:Array;

    /**
     *  @private
