configure a default user for each seat in the GTK greeter

[beroal]

My computer has 2 seats. Each seat mostly is used by one person, for example, Seat 0 is used by Person 0. Person 1 uses Seat 0 occasionally. So I want LightDM to show the account of Person 0 chosen on Seat 0 in the GTK greater and to move the focus to the password field. For convenience. This solution http://askubuntu.com/a/59227/117043 does not work. I don't think that a default user should be configured in AccountsService because it has no concept of seats. (This is just my guess. AccountsService is undocumented.)

[beroal (beroal)]

I see now that the greeter shows the user account chosen the last time. This partially solves my problem.

[beroal (beroal)]

The GTK greeter remembers one user account for all seats. This is not what I need.