Seems to be a problem only with active directory users (so related to the usage of pam_winbind.so).
I tried this on a new installed machine:
created a user newuser
chage -M 5 newuser (set expiring password to 5 days)
lightdm logs in showing a warning for the expiring password (disappears very quickly because lightdm closes)
I'll try this also on my client machine (in few days) and i'll test also with another expiring Active Directory user.
Seems to be a problem only with active directory users (so related to the usage of pam_winbind.so).
I tried this on a new installed machine:
created a user newuser
chage -M 5 newuser (set expiring password to 5 days)
lightdm logs in showing a warning for the expiring password (disappears very quickly because lightdm closes)
I'll try this also on my client machine (in few days) and i'll test also with another expiring Active Directory user.