In 1978, Maurice Sendak began to design a new production of Mozart’s “Magic Flute,” which débuted in Houston two years later. (A diorama of a scene in the second act is pictured above.) A dozen Sendak-designed operas and ballets followed. He often turned to the archives of the Morgan Library for inspiration and later returned the favor, bequeathing nine hundred of his preparatory works to the museum. The exhibition “Maurice Sendak: Drawing the Curtain” opens on June 14.