Ernst Lubitsch’s first talkie and first operetta, costarring Maurice Chevalier and Jeanette MacDonald, shares with the other two 1929 features showing at the Music Box on Thursday the excitement of movies being reinvented, so that silence as well as sound becomes a brand-new plaything (in contradistinction to “silent” movies, which usually had musical accompaniment). A study in playfulness, this fantasy about a country preoccupied with its queen getting married actually has a dog barking out half a chorus of one number, perfectly in tune, and the pre-Code erotics and sexual politics seem pretty advanced in spots. Secondary leads Lillian Roth and Lupino Lane offer some acrobatic low comedy as servants whose best song is called “Let’s Be Common.” 110 min. Also on the program is the silent short Big Business (1929), Laurel and Hardy’s classic grudge match with Jimmy Finlayson.