where to use the xdm host chooser?

[Zhang Weiwu]

Hello. Now I have my /usr/X11R6/lib/X11/xdm/Xaccess contain (only) this:
*   CHOOSER BROADCAST

according to xdm(1) this will enable XDMCP host chooser upon user login. 
Now I reboot, xdm login box pops up, everything like it was before.

I thought there will be a bottom to click to launch the chooser (like 
gdm -> system -> Run XDMCP host chooser), or there will be a list of 
clickable hosts to send query to. Any hints?

Thank you.