hello,
thanks for your feedback.
The debian changelog for lightdm-gtk-greeter 1.8.4-1 only says "new upstream version",
but the upstream releasenotes do point out, that 1.8.3-1 didn't fix the exit bug:
- Really fix exit bug (LP:
#1290575 )
So I will mark the issue as solved (for now).
greetings
musca