Dart Flutter 布局：如何在 Flutter 中将 Row 放入 Flex(或另一个 Row)中还使用堆栈小部件

我需要将2个合成的小部件放入一个Row:

合成的小部件被命名为"boxText".我需要两次，每次都在有两个Texts和TextFormField的边界内:

Stack
  Image and others
  Form
    Row or Flex or Whatever:
    +------------------------------+    +------------------------------+
    | Text  Text TextFormField     |    | Text Text  TextFormField     |
    +------------------------------+    +------------------------------+

我的代码(和眼泪):

@override
Widget build(BuildContext context) {
// Composed Widget
 Widget boxText = new Container(
  decoration: new BoxDecoration(
    border: new Border.all(
      color: Colors.cyan[100],
      width: 3.0,
      style: BorderStyle.solid,
    ),
  ),
  margin: new EdgeInsets.all(5.0),
  padding: new EdgeInsets.all(8.0),
  child: new Row(
    crossAxisAlignment: CrossAxisAlignment.start,
    children: <Widget>[
      new Text(
        'Text',
        style: null,
      ),
      new Text(
        'Text',
        style: null,
      ),
      new TextFormField(
        decoration: const InputDecoration(
          hintText: '',
          labelText: 'label',
        ),
        obscureText: true,
      ),
    ],
  ),
);

return new Scaffold(
  key: _scaffoldKey,
  body: new Stack(
    alignment: AlignmentDirectional.topStart,
    textDirection: TextDirection.ltr,
    fit: StackFit.loose,
    overflow: Overflow.clip,
    children: <Widget>[

      new Container(
        color: Colors.red[200],
        margin: new EdgeInsets.only(
          left: MediaQuery.of(context).size.width * 0.05,
          right: MediaQuery.of(context).size.width * 0.05,
          top: MediaQuery.of(context).size.height * 0.4,
          bottom: MediaQuery.of(context).size.height * 0.1,
        ),
        width: MediaQuery.of(context).size.width,
        height: MediaQuery.of(context).size.height,
        child: new Form(
          key: _formKey,
          child: new ListView(
            padding: const EdgeInsets.symmetric(horizontal: 16.0),
            children: <Widget>[
              new Flex(
                direction: Axis.horizontal,
                mainAxisAlignment: MainAxisAlignment.start,
                crossAxisAlignment: CrossAxisAlignment.center,
                children: <Widget>[
                  boxText,
                  boxText,
                ],
              ),
            ],
          ),
        ),
      ),
    ],
  ),
    );
  }

如果可能，如何在没有以下条件的情况下使此小部件工作:

══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞══

The following assertion was thrown during performLayout():

An InputDecorator, which is typically created by a TextField, cannot 
have an unbounded width.

This happens when the parent widget does not provide a finite width 
constraint. For example, if the InputDecorator is contained by a Row, 
then its width must be constrained. An Expanded widget or a SizedBox 
can be used to constrain the width of the InputDecorator or the 
TextField that contains it.

'package:flutter/src/material/input_decorator.dart':

Failed assertion: line 945 pos 7: 'layoutConstraints.maxWidth < 
double.infinity'