stock 5.9 installation, gdm starts by default.
attempt to run
Xnest :1 -query localhost from an xterm
results in blank Xnest.
Same command on 5.2 brings Xnest with login prompt.
according to the gdm config file, remote access is enabled.
$ netstat -a | grep 177
udp 11152 0 *:177 *:*
number '11152' is a queue length which increases with every
Xnest attempt. looks like requests are igonored.
It works if debugging is enabled in /etc/X11/gdm/gdm.conf. However
logout doesn't work.
*** This bug has been marked as a duplicate of 2594 ***