Is this the graphical greeter?  What theme?  It is somewhat likely that the
theme is broken, it needs to mark those buttons correctly so that gdm knows that
they shouldn't appear

no, this is after I select "logout" from gnome... the actions-menu is not
visible on the login-screen, but "shutdown" and "restart" options are still
available on the logout-confirm dialog.

Select logout from the panel or one of the panel menus? That's gnome-session
functionality, IIRC, unrelated to the parallel gdm functionality.

No. If I run xdm I don't have those options...

At least I find it confusing as a user to see options that do nothing ;) And as
an administrator I don't want to have those options available..

and again, this is probably Debian-specific (see 149911)... it is patched so
that a config option SecureSystemMenu should ask root-password to access the
Actions-menu. But, when the menu is completely disabled, the config doesn't
apply to gdmflexiserver (which apparently is where gnome-session gets those
options?)

sorry for the noise.. if you can't reproduce this, close the bug please

No news for this bug, I close it.

Feel free to reopen it with the asked details.