The single set across LaMama's The Downstairs is the Wall.  Not a mock-up of the geographically impossible one threatened for the U.S./Mexico borders, but the equally controversial Israel−Gaza security barrier.  A lightning rod in U.S-Middle Eastern diplomacy, in Amir Nizar Zuabi's Grey Rock, it cannot block creativity or dignity. Zuabi, who also directed his play for the newly-formed Remote Theater, provides a blast-off point for The Occupation.  Part of the wall opens revealing Yusuf (Khalifa Natou), a retired TV repairman and former political prisoner, studying blueprints in his shed.  Without telling his daughter Lila (Fida Zaidan) or young friend Sheik (Motaz Malhis), Yusuf is