FLUTTER select contact page setup

main.dart

import 'package:flutter/material.dart';
import 'package:flutter_sticky_header/flutter_sticky_header.dart';

//-----Start App
void main() => runApp(MyApp());

//-----Entry Point
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return StatelessLink();
  }
}

//-----Statless Link Required Between Entry Point And App
class StatelessLink extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Nested Picker Link',
      home: Test(),
    );
  }
}

//-----Test Widget
class Test extends StatefulWidget {
  @override
  _TestState createState() => _TestState();
}

class _TestState extends State<Test> {
  @override
  Widget build(BuildContext context) {
    double toolBarSize = 50;

    Widget toolBar = Container(
      width: MediaQuery.of(context).size.width,
      height: toolBarSize,
      color: Colors.blue,
      child: Text("tool bar"),
    );

    Widget banner = Container(
      width: MediaQuery.of(context).size.width,
      height: 300,
      color: Colors.orange,
      child: Text("banner"),
    );

    Widget aSection = SliverStickyHeader(
      header: Container(
        color: Colors.pink,
        width: MediaQuery.of(context).size.width,
        height: 35,
        child: Text("section"),
      ),
      sliver: new SliverList(
        delegate: new SliverChildListDelegate([
          Container(
            color: Colors.yellow,
            width: MediaQuery.of(context).size.width,
            height: 500,
          ),
        ]),
      ),
    );

    List<Widget> sections = new List<Widget>();
    sections.add(aSection);
    sections.add(aSection);
    sections.add(aSection);

    sections = new List.from([
      SliverToBoxAdapter(
        child: banner,
      ),
      SliverAppBar(
        pinned: true, //avoid strange padding
        floating: true, //avoid strange padding
        expandedHeight: 0, //avoid strange padding
        bottom: PreferredSize(
          preferredSize: Size(
            MediaQuery.of(context).size.width,
            toolBarSize,
          ),
          child: toolBar,
        ),
      ),
    ])..addAll(sections);

    return Scaffold(
      backgroundColor: Colors.green,
      body: SafeArea(
        child: CustomScrollView(
          slivers: sections,
        ),
      ),
    );
  }
}