As the buttons are small it's quite hard to press them in flight, could you make the buttons semi-transparent and bigger ?

i.e. make the buttons take up a large part of the bottom of the screen, but be 95% transparent with only a small '+' or '-' shown on them, this would make them almost invisible to the eye but allow very easy zooming with fingers in flight.

Steve

Aero AT3-R100, C172 Skyhawk, EGBK Sywell