Gotcha! It also occurs to me, re-reading through various GTK and GtkD docs, that it might be better to subclass ListStore, and just override everything so it doesn't touch ListStore's internal storage. Would this sort of thing work?

Currently overriding anything in the Liststore doesn't have any affect
in the C / Gtk+ side of things.

Rats! That does make perfect sense, thinking about it now. Fortunately, drag reordering is nice, but not critical for my app, so that can wait :)