GtkWidget *const tab = gtk_notebook_get_nth_page(notebook, page_num);
const struct tabtype *const t = g_object_get_data(G_OBJECT(tab), "type");
assert(t != 0);
GtkWidget *const tab = gtk_notebook_get_nth_page(notebook, page_num);
const struct tabtype *const t = g_object_get_data(G_OBJECT(tab), "type");
assert(t != 0);