Here's an interesting thread on what appears to be the newest attempt to reconstruct Richard Williams' animated feature The Thief and the Cobbler. It's a very elaborate bootleg, but apparently of much better quality than scratchy workprint versions of the film that float around.
This feature is the great massacred legend of animation, as famous in its own way as Greed or The Magnificent Ambersons for the studio butchery it suffered. As Eddie Bowers explains, Williams spent over 20 years working on this feature film, borrowing time and money to work on the film whenever possible. Finally he secured a distribution deal with a studio to complete the film, but the studio took the film away from him, re-cut it, re-dubbed it, and re-titled it Arabian Night to make it seem more like an Aladdin knockoff. The product that was released to the public was beautifully animated, since most of the animation was directed by Williams, but it wasn't anything like what it was supposed to be.
The goal of a complete, fully-restored, official release of The Thief and the Cobbler remains a possibility, but, as Wikipedia details, there are problems involving rights, payments, and the preservation of the necessary material. The end result is that animation has its own legend of studio hacks tearing an auteur and his dream project to shreds, and the mystery of what the "real" movie would have been like if the creator had had his way.