无法在抖动中添加垂直线

我更改了代码，例如您提供的树，并将其更改为工作。

请用“ IntrinsicHeight”包装“ Row”。

我附上了经过测试的完整代码。

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Padding(
        padding: EdgeInsets.all(10),
        child: Center(
          child: Column(
            children: [
              Container(
                child: Form(
                  onChanged: () {},
                  child: IntrinsicHeight(
                    child: Row(
                      children: [
                        Expanded(
                          flex: 3,
                          child: Column(
                            children: [
                              Container(child: Text('a')),
                              Container(child: Text('a')),
                              Container(child: Text('a')),
                            ],
                          ),
                        ),
                        Container(
                          child: VerticalDivider(
                            color: Colors.red,
                            width: 1,
                          ),
                        ),
                        Expanded(
                          flex: 2,
                          child: Column(
                            children: [
                              Container(child: Text('a')),
                              Container(child: Text('a')),
                              Container(child: Text('a')),
                            ],
                          ),
                        )
                      ],
                    ),
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}