Some thought they were merely Christmas decorations. Others insisted they were aircraft warning lights. But the truth is the dancing lights ontlining the arches atop Trammell Crow’s Texas Commerce lower are a permanent, year-round, purely aesthetic feature. The sixty-tour strobe lights-thirty-two on the north and thirty-two on the south sides of the building-were red and green during the holidays but have been changed to a nonseasonal white. Building manager Jim Seal says that in order to add something “interesting and new” to the Dallas shyline, the computer-driven lighting system, which cost nearly $150,000, shorn the time by flashing the lights at the top of each hour.