[Gtk-sharp-list] GInterfaces not working

[Dave Glick]

> I commented on the bug already, but is this only on win32?

We've tested it on 2.4.3 and 2.6.1 on both Linux and Windows. The only
combination that seems to have trouble is 2.6.1 on Windows. My immediate
concern is that we use Mono on Windows and require GInterface support for
some custom tree models. More generally, since this looks like some kind of
regression and appears to be fairly low-level I'm concerned about what else
might be affected by this bug that we haven't discovered yet (on either
platform).