Equivalent of the gtk g_object_ref/unref functions in gtkmm?

[Jef Driesen <jefdriesen hotmail com>]

When I look at some gtk C code, I see everywhere pointers to widgets 
(and other things). As i understand all gtk objects are reference 
counted to keep the objects alive until the last pointer is released.

How does that work in gtkmm? At first sight, gtkmm widgets doesn't seem 
to be reference counted, because something like this does not work 
(because of the private copy constructor):

Gtk::Button a, b(a);

Do I need to use smart pointers (e.g. boost::shared_ptr) for that? Does 
that means the underlying gtk reference counting mechanism is not used 
in gtkmm?

I read in the gtkmm documentation there is a Glib::RefPtr, that uses the 
internal gtk/gobject reference counting. If I understand that correctly, 
I can use this smart pointer (instead of third party implementation like 
boost)?

Glib::RefPtr<Gtk::Button> a(new Gtk::Button()), b(a);

But I've never seen that before, only with non-widgets objects like 
pixbufs and treemodels.

One of the problems I'm trying to solve is I want to create a treeview 
that will act as a sidebar pane in my application. And I would like to 
store a reference to other widgets (which are in a notebook) in the 
treemodel. When the user activates an item in the treeview, the 
corresponding widget should be displayed in the main application pane 
(by displaying the correct notebook page). How should this treemodel 
look like in gtkmm? Is a smart pointer going to interfere with the 
automatic memory management when I add the widget to the notebook? Do I 
need smart pointers at all for all this?