Gtk::Viewport viewport (*hadj, *vadj);
viewport.add (canvas);
Gtk::VBox overall_box;
overall_box.pack_start (viewport);
overall_box.pack_start (button_box, false, false);
Gtk::Viewport viewport (*hadj, *vadj);
viewport.add (canvas);
Gtk::VBox overall_box;
overall_box.pack_start (viewport);
overall_box.pack_start (button_box, false, false);