static_cast<Gtk::TreeView*>(get_canvas_view()->get_ext_widget(get_name()))
);
Gtk::TreeModel::iterator iter(tree_view->get_selection()->get_selected());
static_cast<Gtk::TreeView*>(get_canvas_view()->get_ext_widget(get_name()))
);
Gtk::TreeModel::iterator iter(tree_view->get_selection()->get_selected());