The case was fascinating in both facts and procedure. The German grandnephew of a Berlin banker claimed his granduncle had been forced to sell a cache of famous Picasso paintings under economic duress from the Nazi regime. He sued for restitution. The Museum of Modern Art and the Guggenheim settled with him last February, but a foundation established by Andrew Lloyd Webber won a motion to dismiss his suit on the grounds that he lacked standing. On Tuesday, the appellate court affirmed the dismissal.