Place cabbage, lemon juice and boiling water in skillet. Cover and cook, stirring once or twice, until cabbage is tender, 10 to 12 minutes. Stir in butter.
Meanwhile, blend together brown sugar, cornstarch and salt. Drain juice from pineapple and blend into cornstarch mixture along with vinegar. Add cornstarch mixture and pineapple bits to cabbage. Cook, stirring, until mixture thickens and bubbles. Serve hot.