//original function

public function initiate(parent:DisplayObjectContainer, tileSize:int, tilesX:int, tilesY:int, screenWidth:int, screenHeight:int, backgroundColor:uint, active:Boolean= true):void {
            if (_initiated) return;
            _initiated = true;

            //tile size and world size
            _tileSize = tileSize;
            _tilesX = tilesX;
            _tilesY = tilesY;
            _boundingWidth = _tileSize * _tilesX;
            _boundingHeight = _tileSize * _tilesY;

            //store screen size
            _screenWidth = Math.min(screenWidth, _boundingWidth);
            _screenHeight = Math.min(screenHeight, _boundingHeight);

            this.backgroundColor = backgroundColor;


            for (var i:int = 0; i < _tilesX * _tilesY; i++) {
                _tiles.push(null);
                _tileObjects.push(new Array());
            }
            _parent = parent;
            if (active) activate();
        }



// The overridden function
override public function initiate(parent:DisplayObjectContainer, tileSize:int=40, tilesX:int=20, tilesY:int=15, screenWidth:int=800, screenHeight:int=600, backgroundColor:uint=0x000000, active:Boolean = true):void
        {
            super.initiate(parent, tileSize, tilesX, tilesY, screenWidth, screenHeight, backgroundColor, active);
        }