Question: When was Kathryn Grayson of the 1946 American musical comedy, Ziegfeld Follies, under contract to Metro-Goldwyn-Mayer?

<P0-S0> Glorifying the American Girl is a 1929 American Pre-Code, musical comedy film produced by Florenz Ziegfeld that highlights Ziegfeld Follies performers. <P0-S1>  The last third of the film (which was filmed in early Technicolor) is basically a Follies production, with cameo appearances by Rudy Vallee, Helen Morgan, and Eddie Cantor. <SEP> <P1-S0> Kathryn Grayson (February 9, 1922 – February 17, 2010) was an American actress and coloratura soprano. <P1-S1>  From the age of twelve, Grayson trained as an opera singer. <P1-S2>  She was under contract to Metro-Goldwyn-Mayer by the early 1940s, soon establishing a career principally through her work in musicals. <P1-S3>  After several supporting roles, she was a lead performer in such films as "Thousands Cheer" (1943), "Anchors Aweigh" (1945) with Frank Sinatra and Gene Kelly, and "Show Boat" (1951) and "Kiss Me Kate" (1953), both with Howard Keel. <SEP> <P2-S0> Dick Williams (born June 7, 1926) is an American singer and actor. <P2-S1>  He is the older brother of Andy Williams and had started out like Andy in The Williams Brothers. <P2-S2>  Williams was born in Wall Lake, Iowa, the son of Jay Emerson and Florence (née Finley) Williams. <P2-S3>  While living in Cheviot, Ohio, Williams attended Western Hills High School in Cincinnati, Ohio. <P2-S4>  He finished high school at University High School, in West Los Angeles, because of his family's move to California. <P2-S5>  Williams had brothers: Bob, Don, and Andy. <P2-S6>  One of his first performance was in a children's choir at the local Presbyterian church. <P2-S7>  He and his brothers formed the Williams Brothers quartet in late 1938, and they performed on radio in the Midwest, first at WHO, in Des Moines, Iowa, In July 1940 the family the family moved to Chicago and received a job at WLS, in Chicago, and WLW, in Cincinnati. <P2-S8>  Moving to Los Angeles in 1943, the Williams Brothers sang with Bing Crosby on the hit record "Swinging on a Star" (1944). <P2-S9>  They appeared in four musical films: "Janie" (1944), "Kansas City Kitty" (1944), "Something in the Wind" (1947) and "Ladies' Man" (1947). <P2-S10> The Williams Brothers were signed by Metro-Goldwyn-Mayer to appear in "Anchors Aweigh" and "Ziegfeld Follies" (1945) but, before they went before the cameras, the oldest brother, Bob, was drafted into military service and the group's contract was canceled. <P2-S11>  Kay Thompson, a former radio star who was now head of the vocal department at MGM, had a nose for talent and hired the remaining three Williams brothers to sing in her large choir on many soundtracks for MGM films, including "The Harvey Girls" (1946). <P2-S12>  When Bob completed his military service, Kay hired all four brothers to sing on the soundtrack to "Good News" (1947). <SEP> <P3-S0> Ziegfeld Follies is a 1946 American musical comedy film released by Metro-Goldwyn-Mayer and directed by Lemuel Ayers, Roy Del Ruth, Robert Lewis, Vincente Minnelli, Merrill Pye, George Sidney and Charles Walters. <P3-S1>  It stars many of MGM leading talents, including Fred Astaire, Lucille Ball, Lucille Bremer, Fanny Brice (the only member of the ensemble who was a star of the original Follies), Judy Garland, Kathryn Grayson, Lena Horne, Gene Kelly, James Melton, Victor Moore, William Powell, Red Skelton, and Esther Williams.