lightdm 1.12 breaks config semantics for multiple X servers

[Eric Levy]

Previously lightdm.conf would allow configuration of multiple instances of the the display manager across multiple instances of the X server, using [Seat:<num>] section headers. These semantics could be used for multiseat setup as well as for using different virtual terminals to switch between X servers.

Newer versions of lightdm ignore [Seat:<num>] sections. Multiseat configuration was changed to be more explicit, but no indication was given of how simply to configure multiple display manager instances bound to different X server instances.

Unless newer versions support undocumented features, it would appear that the functionality of lightdm has regressed.

This regression appears when Ubuntu release is upgraded to 14.10 from 14.04 or earlier. The regression is confirmed in lightdm 1.12.1-0ubuntu1.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Robert Ancell (robert-ancell)]

This was an intentional change:
http://lists.freedesktop.org/archives/lightdm/2014-August/000661.html

From the NEWS file:

Overview of changes in lightdm 1.11.7

    * Use logind to provide the list of seats to use. Deprecate the old method
      of manually defining seats.
    * Add --show-config option that shows combined configuration.
    * Drop the surfaceflinger seat type. This was a temporary solution while
      Ubuntu Phone was migrating to Mir.