Question: Jeanette MacDonald and Maurice Chevalier famously made many films in the 1930s. In which one did she play a princess?

Context articles: Monte Carlo (1930 film)
Break the News (film)
The Merry Widow (1934 film)
One Hour with You
The Love Parade
Gabriel Scognamillo
Love Me Tonight
Jeanette MacDonald
Sharon Rich
Mimi (song)

Monte Carlo is a 1930 American Pre-Code musical comedy film, directed by Ernst Lubitsch.
 It stars Jeanette MacDonald as Countess Helene Mara.
 The film is notable for the song "Beyond the Blue Horizon", which was written for the film and was performed by Jeanette MacDonald.
 The film was also hailed by critics as a masterpiece of the newly emerging musical genre.
 The screenplay was based on the Booth Tarkington novel "Monsieur Beaucaire".
Break the News is a 1938 British musical comedy film directed by René Clair and starring Jack Buchanan, Maurice Chevalier and June Knight.
 Two struggling performers decide to create a fake murder scandal in order to drum up publicity for their act.
 It was based on the novel "Le mort en fuite" by Loïc Le Gouriadec which had previously been made into a 1936 French film "Death on the Run".
 Songs featured include "It All Belongs to You" (Cole Porter, sung by Chevalier) and "We're Old Buddies" (Van Phillips, Jack Buchanan, sung by Chevalier and Buchanan).
The Merry Widow is a 1934 film adaptation of the operetta of the same name by Franz Lehár.
 It was directed and produced by Ernst Lubitsch and starred Maurice Chevalier and Jeanette MacDonald.
 A French-language version was produced at the same time and released in France the same year as La Veuve joyeuse.
One Hour with You is a 1932 American Pre-Code musical comedy film about a married couple who find themselves attracted to other people.
 It was produced and directed by Ernst Lubitsch "with the assistance of" George Cukor, and written by Samson Raphaelson, from the play "Only a Dream" by Lothar Schmidt.
 It stars Maurice Chevalier, Jeanette MacDonald and Genevieve Tobin and features Charles Ruggles and Roland Young.
 A French-language version, called "Une heure près de toi" was made simultaneously, with Lili Damita playing Genevieve Tobin's role.
The Love Parade is a 1929 American Pre-Code musical comedy film about the marital difficulties of Queen Louise of Sylvania (Jeanette MacDonald) and her consort, Count Alfred Renard (Maurice Chevalier).
 Despite his love for Louise and his promise to be an obedient husband, Count Alfred finds his role as a figurehead unbearable.
Gabriel Scognamillo (27 October 1906 – 31 May 1974) was an Italian art director.
 One of the first films he worked on was Jean Renoir's provocative 1931 film "La Chienne".
 Two years later he had moved to Hollywood where one of his first films there was MGM's production of "The Merry Widow" (1934) with Maurice Chevalier and Jeanette MacDonald.
Love Me Tonight is a 1932 American Pre-Code musical comedy film produced and directed by Rouben Mamoulian, with music by Rodgers and Hart.
 It stars Maurice Chevalier as a tailor who poses as a nobleman and Jeanette MacDonald as a princess with whom he falls in love.
 It also stars Charles Ruggles as a penniless nobleman, along with Charles Butterworth and Myrna Loy as members of his family.
Jeanette Anna MacDonald (June 18, 1903 – January 14, 1965) was an American singer and actress best remembered for her musical films of the 1930s with Maurice Chevalier ("The Love Parade", "Love Me Tonight", "The Merry Widow" and "One Hour With You") and Nelson Eddy ("Naughty Marietta", "Rose-Marie", and "Maytime").
 During the 1930s and 1940s she starred in 29 feature films, four nominated for Best Picture Oscars ("The Love Parade", "One Hour with You", "Naughty Marietta" and "San Francisco"), and recorded extensively, earning three gold records.
 She later appeared in opera, concerts, radio, and television.
 MacDonald was one of the most influential sopranos of the 20th century, introducing opera to movie-going audiences and inspiring a generation of singers.
Sharon Rich (born June 11, 1953) is an author and film historian, best known for the biography "Sweethearts" about 1930s singing stars Jeanette MacDonald and Nelson Eddy.
 She was close friends for many years with Jeanette's older sister, actress Blossom Rock (aka Marie Blake).
 Along with interviewing hundreds of people, Rich had access to many collections of private letters, Eddy’s personal scrapbooks, diary entries, FBI files and MacDonald’s unpublished autobiography.
 As follow up documentation to "Sweethearts", Rich has written several additional books and edited and written over seventy magazine articles.
 In 1995 she was awarded a Dame of Merit by the Knights of Malta for her contribution to History and Literature.
"Mimi" is a popular song written by Richard Rodgers, with words by Lorenz Hart.
 It was featured in the movie "Love Me Tonight" (1932), in which it was first sung by Maurice Chevalier to Jeanette MacDonald, then later reprised by the entire company.
 Sergio Franchi performed this song January 2, 1964