import 'package:flutter/material.dart'; class Header extends StatelessWidget implements PreferredSizeWidget { final String title; final Function() onSidebarToggle; const Header({Key? key, required this.title, required this.onSidebarToggle}) : super(key: key); @override Size get preferredSize => Size.fromHeight(60); @override Widget build(BuildContext context) { return AppBar( title: Text(title), actions: [ IconButton( icon: Icon(Icons.menu), onPressed: () { onSidebarToggle(); // Einblenden der Sidebar }, ), ], ); } }