[Pkg-xfce-devel] Bug#715151: lightdm: Impossible to login when there are more than ~15 user accounts

Hamish hamish_b at yahoo.com
Sat Jul 6 09:57:50 UTC 2013

Package: lightdm
Version: 1.2.2-4
Severity: important


observed in lightdm version 1.2.2-4 from Wheezy:

It is not possible to use LightDM on a system with more that about 10-15
users. We happen to have many more than that, but it may be that even 8
users exceed the 1024 pixel height of a standard monitor? The list of
names scrolls off the top and bottom of the screen and trying to move
higher up or lower down with the arrow keys lets you adjust the selected
user off-screen, but unless you have access to the passwd file and are
good at counting there's no way to know who's highlighted once it's off
screen. Also the password box is off the bottom of the screen, so even
if you are lucky to have a name in the middle of the alphabet & so have
your name show up on screen you have type your password blindly and
press enter... The user name selector box needs a max height and a
scroll bar.

EDID detection of the monitor in /etc/log/Xorg.0.log looks fine.

Also, it's not clear to me: what controls if a login name is a single 
line tall, or if it gets (seemingly) a newline before and after it so 3 
lines per name. Maybe that is reserving space for a NULL 60x60 avatar 
icon? If we could get that down to 1 line per user it would help mitigate 
the effects of the missing scrollbar.

I suspect once you try lightdm on a system with hundreds or thousands
of users without picking a with-names-list theme, eventually you'll
exceed 32k pixels and the X server will become quite unhappy about

here is a bash snippet to run for easy re-creation.

for i in `seq -f'%02.0f' 50` ; do
   adduser testuser_$i --disabled-password --gecos "Test user $i,,,"

for i in `seq -f'%02.0f' 50` ; do
   deluser --remove-home testuser_$i

I attach a screenshot.


see also ubuntu 12.04 LTS version of this bug:
and related to, but not a duplicate of launchpad #1047140 "lightdm
 window manager selection overshoots  physical screen size"
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