The first time 'The Real Thing' came to Broadway, it won the Tony Award for best play. The next time it arrived, it won for best play revival. This time it just may sneak away with the trophy for best musical revival. A thoroughly excellent and tuneful version of Tom Stoppard's brilliant play about love and fidelity opened Thursday at the American Airlines Theatre, directed by Sam Gold and featuring a dozen songs, both sung onstage by the actors between scenes or wafting out of record players...Some may grouse that they may be a little too on-point for such a slippery play, but the actors integrate them well...The seven-member cast is first-rate...McGregor rarely lets his mask down, but when he does -- moaning alone or quietly sobbing -- it's heartbreaking. Maggie Gyllenhaal plays Annie...with a fierce opaqueness, her face decorated with a clever, knowing smile or a cool standoffishness. Gyllenhaal telegraphs her character's unease and real desires with aching subtlety...If this play is almost 30 years old, its age wasn't visible.