The new addition to the Seattle Art Museum, which opened last summer, provides one answer: an anti-icon. Instead of architectural pyrotechnics, the designer, Brad Cloepfil of Allied Works Architecture, opted for what, at first glance, appears to be almost corporate blandness. Almost, but not quite. The dull stainless steel suits the often overcast Northwest light, and the sliding shutters that control light entering the galleries create changing patterns on the exterior wall. The upper floors of this loftlike building, currently leased as offices, can be converted into gallery space in the future, when the museum expands. This pragmatic approach gives the museum maximum flexibility, although at the price of somewhat uninspired interiors.