I managed to have a rather large box as hand-carry on a flight from PVG-HKG with China Eastern which wouldn't fit in the overhead locker so they buckled it to the free seat next to me.

On transferring to a CX flight at HKG they told me that the box was far to big to take as carry-on and I had to check it in. The flight wasn't full so I asked them if they could do what MU did and just strap it to the seat next to me. They said no but I did get upgraded to business from economy so can't complain! Different airlines, different rules, but MU are certainly more 'laissez faire' when it comes to carry-on baggage.