import 'package:flutter/material.dart' hide MenuItem;
import 'package:tray_manager/tray_manager.dart';

await trayManager.setIcon(
  Platform.isWindows
    ? 'images/tray_icon.ico'
    : 'images/tray_icon.png',
);
Menu menu = Menu(
  items: [
    MenuItem(
      key: 'show_window',
      label: 'Show Window',
    ),
    MenuItem.separator(),
    MenuItem(
      key: 'exit_app',
      label: 'Exit App',
    ),
  ],
);
await trayManager.setContextMenu(menu);

import 'package:flutter/material.dart';
import 'package:tray_manager/tray_manager.dart';

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> with TrayListener {
  @override
  void initState() {
    trayManager.addListener(this);
    super.initState();
    _init();
  }

  @override
  void dispose() {
    trayManager.removeListener(this);
    super.dispose();
  }

  void _init() {
    // ...
  }

  @override
  Widget build(BuildContext context) {
    // ...
  }

  @override
  void onTrayIconMouseDown() {
    // do something, for example pop up the menu
    trayManager.popUpContextMenu();
  }

  @override
  void onTrayIconRightMouseDown() {
    // do something
  }

  @override
  void onTrayIconRightMouseUp() {
    // do something
  }

  @override
  void onTrayMenuItemClick(MenuItem menuItem) {
    if (menuItem.key == 'show_window') {
      // do something
    } else if (menuItem.key == 'exit_app') {
       // do something
    }
  }
}