LOOKIN' ROSY

Proof positive that Roseanne Arnold did more than munch loose-meat sandwiches on her summer break: At the opening of Planet Hollywood in Chicago last week, she premiered her new nipped-and-tucked look for the fall TV season. Ignoring questions about her fresh face, Barr spent the evening rounding up guests for her sitcom. As Sharon Stone was arriving, Barr shouted, ''Hey, Sharon, will you be on my show in the fall?'' ''Uh, yeah,'' said Stone. ''I think I'm free some time in September.''