The gay divorcee: Oscar-winner The Continental revels in precision-dance joy, Cole Porter's Night and Day sways with timeless grace, and Fred and Ginger's first top billing sets the tone for more film hits to come. Top hat: Dale Tremont confuses showman Jerry Travers with another man, and is alternately charmed and disgusted by his advances, because she thinks he's married. Shall we dance: A George and Ira Gershwin score has Fred tapping to Slap That...