The Berkshire Museum says it and the Massachusetts attorney general's office are moving forward on an agreement related to the museum's future and its controversial decision two sell two Norman Rockwell artworks to fund an expansion. The agreement was announced late Friday. As part of the deal, which must be approved by the Massachusetts Supreme Judicial Court, the museum would sell Rockwell's "Shuffleton's Barbershop," not at a Sotheby's auction as originally planned, to an unnamed American nonprofit museum. That buyer has agreed to display the artwork and to loan it to the Norman Rockwell Museum in Stockbridge for 18-24 months. It also will consider loaning it to other Massachusetts museums in the years to follow.