[vishnu]

Disclaimer: Rant mode; not really looking for help. So, in 30 some years of programming with Xt and Motif, I finally stumbled onto an opportunity to use XtAddCallbacks, which apparently  no one else ever uses. And now I know why. Because to use it you have to pass in as a parameter an XtCallbackList. I have here in my lap Volume 4 of the X Toolkit Intrinsics Programming Manual, this is what it says about XtCallbackList:

Yes, you read that right, what it says about XtCallbackList is NOTHING. And of course the GNU compiler is so helpful (image attached). Rant mode off, kindly resume your normal activities...