While it is very nice to be able to send messages from the main to the secondary screen, it would be greatly useful to be able to send secondary->main messages as well.
Examples of use:
Game controller on main, game view on secondary - when game is won on secondary, change UI on main (or send score for leaderboard, etc)
Media player on secondary, controls on main - lock controls on main while media loading on secondary
While it is very nice to be able to send messages from the main to the secondary screen, it would be greatly useful to be able to send secondary->main messages as well.
Examples of use: