tfield_bool * register_bool(const std::string &id, const bool mandatory, const std::function< bool()> &callback_load_value=std::function< bool()>(), const std::function< void(const bool)> &callback_save_value=std::function< void(const bool)>(), const std::function< void(twidget &)> &callback_change=std::function< void(twidget &)>())
Creates a new boolean field.