yet another ddd 3.3.12 MacOS Xt error

[ Already posted the following to bug-ddd, but no response there so I'm 
following up here -- apologies to anyone reading both lists. ]

I too am getting the same fatal

Xt error: Unresolved inheritance operation

ddd startup-time error under MacOS as many others have reported here recently, 
using both Sierra and El Capitan. I won't bother repeating the same details 
that everyone else has already reported, mine are essentially identical.

I do wonder if this has something to do with the fact that on my systems, which 
use MacPorts for both the ddd and prerequisite OpenMotif package installs, the 
more recent MacPorts OpenMotif package could only be installed after I had 
pre-installed libXt (the source of the ddd error) with the modified 
installation command

# sudo port install xorg-libXt +flat_namespace

(modified with regard to the newly-required +flat_namespace option).

I have two questions for the ddd-on-MacOS community at large:

(1) Is ddd still working for ANYBODY out there on recent MacOS/ddd/XQuartz 
releases?

(2) Are others, either with or without the ddd Xt inheritance error, using the 
same +flat_namespace libXt install flag as I did? I'm not certain that ddd 
stopped working at exactly the same time as I upgraded my OpenMotif with this 
flag as I use it infrequently under MacOS, but I am suspicious. Not sure that 
it makes any difference as I can't install OpenMotif without that flag, but it 
might point the way to the fix.

Thanks,

Roger Davis
Univ. of Hawaii