If logout would be followed by gdm-greeter, there would not be an option to return to a session. Anyway, I can't reproduce the second part. I mean all the buttons work in gnome-screensaver (Version: 2.24.0-0ubuntu2) unlock dialog. (gdm Version: 2.20.8-0ubuntu3). I am using Intrepid.
If logout would be followed by gdm-greeter, there would not be an option to return to a session. Anyway, I can't reproduce the second part. I mean all the buttons work in gnome-screensaver (Version: 2.24.0-0ubuntu2) unlock dialog. (gdm Version: 2.20.8-0ubuntu3). I am using Intrepid.