      */
     public function insertColumns(startColumn:int, count:int):void
     {
-        GridDimensions.insertValueToVector(cellHeights, startColumn, count, 0);
+        GridDimensions.insertValueToVector(cellHeights, startColumn, count, -1);
     }
     
     /**

     */
    public function clearColumns(startColumn:int, count:int):void
    {
        GridDimensions.clearVector(cellHeights, 0, startColumn, count);
        updateMaxHeight();
    }
    

        }
        
        const changed:Boolean = maxCellHeight != max;
        if (changed)
            maxCellHeight = max;
        return changed;
    }
    
