ddd hangs on plot, crashes with 'BadWindow' error on cancel

Hi all,

    Sorry if this is already covered "somewhere", I've done my level 
best trying to figure it out.
    I'm having the same problem Robert Atwood was having three years ago 
(stale thread: 3.3.9/gnuplot 4.0 / bad X, swamped by Russian SPAM...):

    1) Start ddd with my little test program, run, print & display array 
- OK
    2) Try plot - get "Starting gnuplot..." window - gnuplot processes 
are started, but nothing else happens.
    3) Press "Cancel" and ddd crashes with the messages:

X Error of failed request:  BadWindow (invalid Window parameter)
  Major opcode of failed request:  10 (X_UnmapWindow)
  Resource id in failed request:  0x0
  Serial number of failed request:  23997
  Current serial number in output stream:  24000

X error (invalid Window parameter).

    Setup: I am working locally on a Ubuntu 5.10 system. I have tried

*ddd 3.3.9
ddd 3.3.11
ddd 3.3.12-test2

    with

*gnuplot 4.0.0-2
 gnuplot 4.2

    (*=versions that come with Ubuntu 5.10, the others I have downloaded 
and built myself)
    Behaviour is the same in all cases.

   If anybody has a hint on how to fix or debug this, I'd greatly 
appreciate it.
   Thanks,

Mike.