any confirmation?
Most coupons work in store on GC. The problem you run into most of the time is the cashier not letting you use it. Very Very YMMV
How about if you purchase another item, get a clueless cashier and you'll be good to go.
According to the below SD report, the 20% off at Staples coupon works even on gift cards as long as there is an eligible item in the order. YMMV, but if this works, it's nice http://www.staples.com/coupons
Any link to coupon