您可以使用window_manager，它有助于找到焦点。

import 'package:flutter/cupertino.dart';
import 'package:window_manager/window_manager.dart';

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

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

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

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

 
  @override
  void onWindowFocus() {
    // do something when app gets into focus state
  }

  @override
  void onWindowBlur() {
    // do something when app gets into inactive/blur state
  }
}