A  quality of Maureen Stapleton, one of the stars of Toys in the Attic, an exercise by Lillian Hellman about a New Orleans family violently disabused of its fantasies, is an impressive capacity for audible rumination. This turns out to be at once comical, prickly, disarming and comfortable, rather than-as it might, with a slight jar-flat, presumptuous, tiring and uncomfortable. Miss Stapleton seems genuinely incredulous whenever apprised of the fact. She has an unwavering image of herself as an inarticulate groundling of Irish descent from Troy, New York. “Peasant stock, kid, sturdy peasant stock, or I’d’ve been dead by now,” she started out recently, for example, with a broad declaratory swipe, and then racketed off into a long discursion that somehow held together.