rem: this.grid[i].unshift(tile); 
add: row.unshift(tile); 
context:     shiftColumn: function(prepend) {        var deltaX = (prepend) ? -this.tileSize.w : this.tileSize.w;        var resolution = this.map.getResolution();        var deltaLon = resolution * deltaX;        for (var i=0; i<this.grid.length; i++) {            var row = this.grid[i];            var modelTileIndex = (prepend) ? 0 : (row.length - 1);            var modelTile = row[modelTileIndex];                        var bounds = modelTile.bounds.clone();            var position = modelTile.position.clone();            bounds.left = bounds.left + deltaLon;            bounds.right = bounds.right + deltaLon;            position.x = position.x + deltaX;            var tile = prepend ? this.grid[i].pop() : this.grid[i].shift();            tile.moveTo(bounds, position);            if (prepend) {                this.grid[i].unshift(tile);            } else {                this.grid[i].push(tile);            }        }    },
meta: 1027	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/1027/24d4fdc1bd0a579276aae125ee7dfada18b1c503/Grid.js/clean/lib/OpenLayers/Layer/Grid.js