Andres, also would you be able to test booting Maverick via a livecd with this monitor configuration, using gnome-display-properties to configure things, and see if you get the same bug there? If it works properly on maverick, that would tend to confirm seb's hypothesis that it's not a gnome regression. If it does happen there, then it would make me the more convinced that it's something wrong in gnome-display-properties.
Andres, also would you be able to test booting Maverick via a livecd with this monitor configuration, using gnome-display- properties to configure things, and see if you get the same bug there? If it works properly on maverick, that would tend to confirm seb's hypothesis that it's not a gnome regression. If it does happen there, then it would make me the more convinced that it's something wrong in gnome-display- properties.