no error message on lost connection (regression from 1.4)

I think Dave fixed one of the cases that caused this a few revs ago, but
another one still remains. Steps to reproduce:

In pgAdmin 1.4.2:

* connect to a configured DB running on a networked machine
* open query
* issue a query
* observe result set
* disconnect your network connection (plug out and back in your cable,
e.g.)
* issue the query again
* get meaningful error message:
 server closed the connection unexpectedly   This probably means the server terminated abnormally   before or while
processingthe request. 

In pgAdmin 1.6 RC1 (5574M):

* repeat the exact same steps as above
* get message ":" (just a colon) in the message window

George