ev_window_set_action_sensitive (ev_window, "ViewContinuous", has_pages);
ev_window_set_action_sensitive (ev_window, "ViewDual", has_pages);
ev_window_set_action_sensitive (ev_window, "ViewBestFit", has_pages);
ev_window_set_action_sensitive (ev_window, "ViewContinuous", has_pages);
ev_window_set_action_sensitive (ev_window, "ViewDual", has_pages);
ev_window_set_action_sensitive (ev_window, "ViewBestFit", has_pages);