He penned the lines. Walter Donaldson, George Gershwin and others provided the music. Yet there was a more vital partner in lyricist Gus Kahns life: Grace LeBoy Kahn, who put the love into his love songs.Doris Day and Danny Thomas are the Kahns in this affectionate musical, one of 1952s top box-office hits. The title song, It Had to Be You, Makin Whoopee and Love Me or Leave Me lead a 23-song cavalcade (in all, he cowrote some 800 tunes) that propels this story of Kahns life from the day he walked into a music publishing house to public triumphs, private failures, career decline and comeback. Directed by Michael Curtiz, this is a winning tribute to the talented guy who put into son what lovers feel in their hearts.