ssh -X when X server is not running

[Dave Yost]

Hi.

On Mac and Cygwin, if your X server is not running, and you ssh -X to 
another host, you get this message:

   Warning: No xauth data; using fake authentication data for X11 forwarding.

This situation can be hard to diagnose for a new user.  A message 
that says something to the effect of

   Is your X server running?

in addition or instead would be good.

Dave