basic_layout.dart

Widget build(BuildContext context) {
    //get the screen width  
    screenWidth = MediaQuery.of(context).size.width;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: <Widget>[
        Container(
          height: 24,//status bar height
          width: cWidth,
          color: Colors.green,
        ),
        Flexible(
          child: ListView(
            controller: controller,
            children: List.generate(
                20,
                (index) => ListTile(
                      title: Text(index.toString()),
                    )),
          ),
        ),
      ],
    );
  }