GtkPlug/GtkSocket workaround for Bonobo

[Nat Friedman <nat helixcode com>]

Maciej Stachowiak writes:
 > 
 > We really need the following change for Nautilus work. OK if I check
 > it in? I checked that Bonobo still works with it in both the in-proc
 > and out-of-proc control cases, and I am pretty sure the memory
 > management works out properly.

    I like this patch.  I haven't tested it, but it looks ok to apply
from reading it.  You'll have to update it for my new megabreakage,
though (sorry).

Nat