In December of 2008, Gergely Barki was at home in Budapest watching Stuart Little with his daughter when he spotted a familiar painting in the background of one of the scenes. Thinking his eyes were playing tricks on him, he leapt off the couch and brought his face close to the television, wiping the screen with his hand so he could get a better look at the painting. “It can’t be real!” he thought. Intrigued, Barki, an art historian at the National Gallery in Budapest, called Sony Pictures and  tracked down the film’s set designer, who was living in the Washington D.C. area. She told him had originally purchased the piece for…