Back Gammon at 30,000 Feet

How much spare space??

Spoiler Alert: This is a gripe about how little space you get in economy seats when the next passenger is a "LARGE" sized person.

This morning I was sitting next to someone on my Qantas A330 flight from Melbourne to Perth who played Back Gammon on his iPad for the full 4 hours of the flight.

Problem: Every move he made on his iPad meant that his elbow nudged my arm... whether we were staking out the arm rest or whether I had my arm well within the space of my seat.

Not wanting to make a scene I did nothing about it other than to quietly stew for the full trip.

Mmmm.... I wonder what I should have, apart from upgrading to Business,
 done??