can't select user from "User Bar" on live image

[Oliver-henshaw]

When I log out of the kubuntu livecd I can't log in again. This seems to be a problem with the "User Bar" theme.

1. Boot into kubuntu-12.10-desktop-amd64.iso
2. Logout
3. Observe login screen

Actual Results: No user icons, just a password field. Entering a blank password doesn't do anything.

Expected results: Ability to select the kubuntu user, enter a blank password and login in again.

Additional Info:

- Entering the "Password and User Account" kcm and changing the image (from a grey box) on the top right doesn't change anything.
- Changing to the "Classic" theme allows me to type in "kubuntu" as the username, give a blank password and log in.

Packages Affected:

lightdm 1.4-0ubuntu2
lightdm-kde-greeter 0.3.0-0ubuntu2

[Nightfall (someoneelse)]

Tested with today's daily iso (Kubuntu raring) - still broken (same behavior as described above).

Packages affected:

lightdm 1.5.3-0ubuntu1
lightdm-kde-greeter 0.3.1-1ubuntu1

[Launchpad Janitor (janitor)]

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

[Nightfall (someoneelse)]

Testing with the "User Bar" theme:

When you create an additional user (say "test", password "test") with default settings (groups etc.) in the "User Management" KCM, (only) this user is displayed on the login screen, can be selected and is able to login.

"kubuntu" user ID: 999
"test" user ID: 1000

-> Assumption (note: I do not really know LightDM/AccountsService (config)):
The login screen hides users with UIDs below 1000 (to hide system users), which includes "kubuntu".
The minimum UID of users to show might come from /etc/login.defs via accountsservice (which overrides /etc/lightdm/users.conf's minimum-uid setting, according to its header comment); see accountsservice's src/daemon.c (this is just a guess though!).

[Nightfall (someoneelse)]

"Live session user" is indeed shown, selectable and able to login if (just for testing!) UID_MIN is set to 999 in /etc/login.defs and accountsservice and lightdm are restarted.

A proper solution might depend on bug #857651.