* glib/Object.cs : switch to ToggleRefs for all items created with
CreateNativeObject. This gets all managed subclasses, with a little
overhang into simple wrappers.
* glib/ToggleRef.cs : new class to manage the weak to strong ref
transitions as a native object flips between shared and unshared
ownership.
* gtk/Object.custom : revamp of the Destroyed signal handling.
* gtk/Gtk.metadata : hide destroy signal so we can deal with it
manually. [Fixes the reopen note of #72018.]
svn path=/trunk/gtk-sharp/; revision=73023
