[gtkmm] Really Glib::free() is needed?

[Igor Gorbounov <igorbounov voronezh serw ru>]

There is written in gtkmm documentation:
(http://www.gtkmm.org/gtkmm2/docs/reference/html/classGtk_1_1TreePath.html#a41)
"Glib::ustring Gtk::TreePath::to_string ( ) const
Generates a string representation of the path.
[...]
Returns:
    A newly-allocated string. Must be freed with Glib::free().
"
and also:
(http://www.gtkmm.org/gtkmm2/docs/reference/html/classGtk_1_1TreeModel.html#a18)
"Glib::ustring Gtk::TreeModel::get_string (const iterator& iter) const
Generates a string representation of the iter.
[...]
Returns:
    A newly-allocated string. Must be freed with Glib::free()."

Well, really Glib::free()?
	Igor Gorbounov