      *  @playerversion AIR 1.5
      *  @productversion Flex 4
      */
-    public function GroupBase(layout:LayoutBase = null)
+    public function GroupBase()
     {
         super();
         tabChildren = true;
-        
-        // our default layout is null.  Otherwise, use the layout 
-        // passed in via the constructor
-        if(layout == null)
-            _layout = new BasicLayout();
-        else
-            _layout = layout;
-        
-    	_layout.target = this;
     }
         
     //--------------------------------------------------------------------------

    //----------------------------------
    //  layout
    //----------------------------------    
        
    private var _layout:LayoutBase;  // initialized in the ctor
    private var _layoutProperties:Object = null;
    private var layoutInvalidateSizeFlag:Boolean = false;
    private var layoutInvalidateDisplayListFlag:Boolean = false;

     */
    public function get horizontalScrollPosition():Number 
    {
        if (_layout)
        {
            return _layout.horizontalScrollPosition;
        }
        else if (_layoutProperties && 
                _layoutProperties.horizontalScrollPosition !== undefined)
        {
            return _layoutProperties.horizontalScrollPosition;
        }
        else
        {
            return 0;
        }
    }

    /**
