         if (_typicalItem == value)
             return;
         
-        typicalItem = value;
+        _typicalItem = value;
         typicalItemChanged = true;
         
         invalidateProperties();

        overlayGroup.layout = new NullLayout();
        addElement(overlayGroup);        
        
        addDownDragUpHandler(this, grid_mouseDownDragUpHandler);
        addEventListener(MouseEvent.MOUSE_MOVE, grid_mouseMoveHandler);
        addEventListener(MouseEvent.ROLL_OUT, grid_mouseRollOutHandler);
        addEventListener(MouseEvent.CLICK, grid_clickHandler);


import spark.layouts.supportClasses.LayoutBase;

class NullLayout extends LayoutBase
{
    public function NullLayout()
