FWIW, this remains broken. A recent update changed my alternatives away from startlxde to startxfce4 (even though they have the same priority and it still thinks the "best version" is the previous setting).
$ update-alternatives --display x-session-manager x-session-manager - auto mode link currently points to /usr/bin/startxfce4 /usr/bin/lxsession - priority 49 slave x-session-manager.1.gz: /usr/share/man/man1/lxsession.1.gz /usr/bin/openbox-session - priority 40 slave x-session-manager.1.gz: /usr/share/man/man1/openbox-session.1.gz /usr/bin/startlxde - priority 50 slave x-session-manager.1.gz: /usr/share/man/man1/startlxde.1.gz /usr/bin/startxfce4 - priority 50 slave x-session-manager.1.gz: /usr/share/man/man1/startxfce4.1.gz /usr/bin/xfce4-session - priority 40 slave x-session-manager.1.gz: /usr/share/man/man1/xfce4-session.1.gz Current 'best' version is '/usr/bin/startlxde'. $ grep x-session-manager /var/log/alternatives.log update-alternatives 2012-03-20 18:58:29: run with --remove x-session-manager /usr/bin/startlxde update-alternatives 2012-03-20 18:58:29: link group x-session-manager updated to point to /usr/bin/startxfce4 update-alternatives 2012-03-20 19:00:18: run with --install /usr/bin/x-session-manager x-session-manager /usr/bin/xfce4-session 40 --slave /usr/share/man/man1/x-session-manager.1.gz x-session-manager.1.gz /usr/share/man/man1/xfce4-session.1.gz update-alternatives 2012-03-20 19:00:18: run with --install /usr/bin/x-session-manager x-session-manager /usr/bin/startxfce4 50 --slave /usr/share/man/man1/x-session-manager.1.gz x-session-manager.1.gz /usr/share/man/man1/startxfce4.1.gz update-alternatives 2012-03-20 19:03:28: run with --install /usr/bin/x-session-manager x-session-manager /usr/bin/startlxde 50 --slave /usr/share/man/man1/x-session-manager.1.gz x-session-manager.1.gz /usr/share/man/man1/startlxde.1.gz -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org