A source at a high-profile US retailer has reportedly confirmed that Apple will be adding a 13-inch Retina MacBook Pro to its notebook lineup at an event later this month. The new 13-inch MacBook would join Apple's 15-inch model in bringing Retina technology -- which first emerged with Apple's iOS devices -- to the notebook space. While the announcement -- indeed, the very existence of a late-October event -- has not been confirmed by Apple, the unveiling of a 13-inch Retina MacBook Pro would be in keeping with previous predictions.