Asserting you use gtk_tree_view_set_model
to swap models.
docbook gtk_tree_view_set_model ()
void gtk_tree_view_set_model (GtkTreeView *tree_view,
GtkTreeModel *model);
Sets the model for a GtkTreeView. If the tree_view already has a model set, it will remove it before setting the new model. If model is NULL, then it will unset the old model.
So this means that if a model is associated with the view its referece counter will decrease by one (I actually verfied that by a look into the source, the documentation is not explicit enough here what "remove" means)).
If you handle it as the example says
/* Create a view */
tree = gtk_tree_view_new_with_model (GTK_TREE_MODEL (store));
/* The view now holds a reference. We can get rid of our own
* reference */
g_object_unref (G_OBJECT (store));
you do not need to do anything additionally unless you explicitly call g_object_ref
or some other method which will add reference.
I strongly suggest you to get devhelp and install the Gtk+
docbook entries.