$ Xnest :2 &
[1] 10667
$ DISPLAY=":2" xterm
AUDIT: Thu Aug 17 01:30:08 2006: 10667 Xnest: client 1 rejected from local host
Xlib: connection to ":2.0" refused by server
Xlib: No protocol specified

xterm Xt error: Can't open display: :2