Specializing in chamber ballets of bygone times, New York Theatre Ballet made a marvelous acquisition in Frederick Ashton's 1930 Capriol Suite. A gloss on 16th-century dance forms, it mingles peasants and aristocrats, lusty ebullience and aloof grace, easy charm and stabs of poignant imagination. Another new-old acquisition, however, is dispensableBalanchine's À La Françaix, a bagatelle in which a feisty girl competes for the boys' attention with a languid sylphide who sheds her virginal white tulle for a red bathing suit. In honor of the ballet master John Taras, who died on April 2, the company danced his 1948 Designs for Strings, an exercise in pure classical style that is, as was its maker, discreet, elegant, and infinitely serviceable. Marco Pelle's brand-new Solitude relates, ineptly, to surrealist ventures of the '30s such as Balanchine's Cotillon and Tudor's Les Mains Gauches, the latter being one of NYTB's resurrections.