 package spark.components
 {
 import flash.display.DisplayObject;
+import flash.events.Event;
 import flash.utils.Dictionary;
 
 import mx.collections.IList;

     */
    override protected function commitProperties():void
    { 
        if (dataProviderChanged || itemRendererChanged)
        {
            dataProviderChanged = false;
            itemRendererChanged = false;
            initializeDataProvider();
            
            mx_internal::maskChanged = true;

    //  layout
    //----------------------------------

    private var useVirtualLayoutChanged:Boolean = false;
    
    /**
     *  @private
     *  Sync the typicalLayoutElement var with this group's layout.
