Stock futures rode narrow gains ahead of Tuesday’s open following a mixed report on durable goods orders and as international markets marked solid gains. Dow futures were 17.2 points above fair market value. Nasdaq 100 futures added a thin 6.3 points, and S&P 500 futures showed a 2-point gain. Small caps were lagging, with Russell 2000 futures sagging 2.3 points below fair market value. The stock market today opens as a half-full cup.