Pare and slice apples. Shred cabbage, cook covered in small amount of boiling salted water for 8 to 10 minutes. Add small amount of vinegar to preserve color. Drain, reserving 1 cup liquid. Place layer of cabbaage in butttered baking dish. Combine grapes, apples, onion, sugar and salt. Arrange in alternate layers with cabbage, making top layer cabbage. Add cabbage liquid and wine. Dot with butter. Cover and bake at 190ºC . for 1 hour. Shake lour over top, mix lightly with fork and bake 15 minutes longer.