If a taller headed screw is used to secure the hook blade instead of the factory slotted screw, it could act as a thumb stud making opening the little zipper a one hand affair. The screw appears to be a metric M3. A M3 socket head cap screw could work if the head diameter is filed to fit in the unthreaded hole. I would have done this already if the the local ACE hardware stocked a SS M3 socket head cap screw.
