wingpanel isn't visible in greeter on NixOS

[worldofpeace]

This has been an issue in NixOS pretty much since we've added Pantheon.

This is what we see in a vm or on a running system

I did confirm that the process is running, it's just that we can't see it.

Interestingly, this was an issue even before the Gtk rewrite. So I'm guessing this is a bug in the compositor? Only because it's the only code path I think was untouched since then.

I'm very open to any requests that could help us debug the issue.

Logs

Only thing I can manage to provide is

• /var/log/lightdm/seat0-greeter.log
  with debug messages.

Don't see anything for the compositor or wingpanel.

Software versions

GTK: 3.24.10
gdk-pixbuf: 2.38.1
mutter: 3.28.4
wingpanel: 2.2.5

At the time of testing the greeter was at 6717a17

[worldofpeace]

We were able to resolve this issue downstream by correcting the system's global environment.