Gamepad focus model (Re: Input and games.)

[Martin Minarik]

I like the second-class seat proposal. got the roughly
same idea
called it a  focus inherit seat.

It's kind of a child seat that is, for some reason, not
capable
to change it's own focus, instead it follows the mother
seat focus.

Nice thing is, the seat  id = player id, making the player
id redundant.

Another nice thing is, the application can still recognize
the seats, making
implementing sub compositor easier.

Most common scenario would be:
 A: joypad 1 on mother seat with keyboard and pointer
 B: joypad 2 on child seat

Let's say:
- user plugs another keyboard and pointer, udev assigns it
to B:
- weston promotes B: to mother seat
The situation is as follows:

 A: joypad 1 on mother seat with keyboard and pointer
 B: joypad 2 on mother seat with keyboard and pointer

The seats are now independent and can control the UI, user
2 can now quit
the focus on the fly. But the question is.. Is this the
expected?
Let's say there is a full screen application and the user
2 presses alt+tab, now
we have a surface stacking/ordering race.

But let's say it got assigned to A:

 A: joypad 1 on mother seat with 2x keyboard and pointer
 B: joypad2 on child seat

So everything is ok, therefore the device-seat assignment
policy would be
used this way to control the expected behavior.