In 1934 four movies--It Happened One Night, Twentieth Century, The Thin Man, and The Gay Divorcee--ushered in the golden age of the Hollywood romantic ("screwball") comedy. Slangy, playful, and "powerfully, glamorously in love with love," the films that followed were unique in their combination of swank and slapstick. Here are the directors--Lubitsch (Trouble in Paradise), Capra (It Happened One Night), Hawks (Bringing...