Since I upgraded Gnome from 2.24 to something more recent, what was then Ctrl+Alt+Del (or
<Control><Alt>Delete speaking of gconf settings) didn’t show the logout dialog anymore, but rather the shutdown/reboot one! I like to be able to log out or switch user with a keyboard shortcut, however, there is no predefined action which would lead to that dialog anymore.
As a workaround, create the following entries in the gnome registry, for example using
/apps/metacity/global_keybindings/run_command_10, enter the keybinding (e.g.
/apps/metacity/keybinding_commands/command_10, use the command
gnome-session-save --logout-dialog --gui — this will do the magic trick of opening the log out dialog.
Disable the old binding to shutdown using
gnome-keybinding-properties by clicking on the entry and hitting backspace, if desired.