Kevin Atherton leads us through a computer-generated exhibit as inventive as it is satirical. The museum is appropriately impossible in its scope, as Atherton playfully acknowledges the imaginative space of virtual worlds. The fantasy exhibitors have free rein in their show, “Four Rooms and a Toilet,” even to the point of cutting windows in partitions, exposing the building’s masonry, and breaking down the wall between the sex-segregated toilets. Atherton, as the gallery guide, justifies each of the artists’ disruptive requests in high-art terminology as we “move” through the rooms.