 import flash.events.Event;
 import flash.utils.Dictionary;
 
-import mx.collections.IList;
-import spark.components.supportClasses.GroupBase;
+import mx.collections.IList;  
 import mx.core.IDataRenderer;
 import mx.core.IFactory;
 import mx.core.IInvalidating;

     */    
    private function changeUseVirtualLayout():void
    {
        trace("DataGroup::changeUseVirtualLayout()");
        cleanUpDataProvider();
        invalidateProperties();
        useVirtualLayoutChanged = true;

                    elt.includeInLayout = true;
                    if (elt is IDataRenderer)
                        IDataRenderer(elt).data = item;
                    if (elt is IItemRenderer)
                        IItemRenderer(elt).labelText = itemToLabel(item);
                    recycledIR = true;
                }
                else 
