The following code demonstrates this problem at closing of the window. This
problem arises in 2.0.0 but not in 1.3.26

#include <gtkmm/main.h>
#include <gtkmm/window.h>
#include <gtkmm/adjustment.h>
#include <gtkmm/spinbutton.h>

struct Win :
	public Gtk::Window
{
	Gtk::Adjustment adj;
public:
	Win() :
		adj(0, 0, 10)
	{
		add(* Gtk::manage(new Gtk::SpinButton(adj)));
	}
	virtual ~Win() {};
};

int main(int argc, char *argv[])
{
	Gtk::Main mainloop(&argc, &argv);
	Win w;
	w.show_all();
	mainloop.run(w);
	return 0;
}