}
      }
      document.addEventListener("visibilitychange", onVisibilityChange);
      const unsubscribe = store.subscribe(function () {
        // This is the key operation of this class, to prevent notification
        // when the panel is hidden.
        if (document.visibilityState == "visible") {
          listener();
        }
      });

      // Calling `subscribe` should return an unsubscribe function
      return function () {
        unsubscribe();
        document.removeEventListener("visibilitychange", onVisibilityChange);
      };
    },

    // Provide expected default store functions
    getState() {
      return store.getState();
    },
    dispatch(action) {
      return store.dispatch(action);
    },
  };
}

exports.visibilityHandlerStore = visibilityHandlerStore;
PK