title: How to display CircularProgressIndicator on top of all widget in a centre of the screen
body: <p>Hi I want to display the <code>CircularProgressIndicator</code> in centre of my screen on top of all widget. it should be like overlay.</p>
  
  <p>Right now when <code>CircularProgressIndicator</code> is visible all widgets move down a bit to display <code>CircularProgressIndicator</code> . I want it should be overlay. Does anyone know how to do that ?</p>
  
  <pre><code>import 'package:flutter/material.dart';
  import 'package:roomie/auth/Auth.dart';
  
  class ForgotPasswordScreen extends StatefulWidget {
    @override
    State&lt;StatefulWidget&gt; createState() {
      return ForgotPasswordScreenState();
    }
  }
  
  class ForgotPasswordScreenState extends State&lt;ForgotPasswordScreen&gt; {
    var emailController = new TextEditingController();
    var authHandler = new Auth();
    bool isLoading = false;
  
    @override
    Widget build(BuildContext context) {
      return new Scaffold(
          body: Container(
              height: MediaQuery.of(context).size.height,
              decoration: BoxDecoration(
                color: Colors.white,
              ),
              child: new Column(
                crossAxisAlignment: CrossAxisAlignment.center,
                mainAxisSize: MainAxisSize.max,
                mainAxisAlignment: MainAxisAlignment.center,
                children: &lt;Widget&gt;[
                  new Row(
                    children: &lt;Widget&gt;[
                      new Expanded(
                          child: isLoading
                              ? Center(child: CircularProgressIndicator())
                              : new Container()),
                    ],
                  ),
                  new Row(
                    children: &lt;Widget&gt;[
                      new Expanded(
                        child: new Padding(
                          padding: const EdgeInsets.only(left: 40.0),
                          child: new Text(
                            "EMAIL",
                            style: TextStyle(
                              fontWeight: FontWeight.bold,
                              color: Colors.redAccent,
                              fontSize: 15.0,
                            ),
                          ),
                        ),
                      ),
                    ],
                  ),
                  new Container(
                    width: MediaQuery.of(context).size.width,
                    margin:
                        const EdgeInsets.only(left: 40.0, right: 40.0, top: 10.0),
                    alignment: Alignment.center,
                    decoration: BoxDecoration(
                      border: Border(
                        bottom: BorderSide(
                            color: Colors.redAccent,
                            width: 0.5,
                            style: BorderStyle.solid),
                      ),
                    ),
                    padding: const EdgeInsets.only(left: 0.0, right: 10.0),
                    child: new Row(
                      crossAxisAlignment: CrossAxisAlignment.center,
                      mainAxisAlignment: MainAxisAlignment.start,
                      children: &lt;Widget&gt;[
                        new Expanded(
                          child: TextField(
                            controller: emailController,
                            textAlign: TextAlign.left,
                            decoration: InputDecoration(
                              border: InputBorder.none,
                              hintText: 'PLEASE ENTER YOUR EMAIL',
                              hintStyle: TextStyle(color: Colors.grey),
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                  Divider(
                    height: 24.0,
                  ),
                  new Container(
                    width: MediaQuery.of(context).size.width,
                    margin:
                        const EdgeInsets.only(left: 30.0, right: 30.0, top: 20.0),
                    alignment: Alignment.center,
                    child: new Row(
                      children: &lt;Widget&gt;[
                        new Expanded(
                          child: new FlatButton(
                            shape: new RoundedRectangleBorder(
                              borderRadius: new BorderRadius.circular(30.0),
                            ),
                            color: Colors.redAccent,
                            onPressed: () {
                              setState(() {
                                isLoading = true;
                              });
                              authHandler
                                  .sendPasswordResetEmail(emailController.text)
                                  .then((void nothing) async {
                                await showDialog(
                                  context: context,
                                  builder: (BuildContext context) {
                                    // return object of type Dialog
                                    return AlertDialog(
                                      content: new Text(
                                          "Password reset email has been sent."),
                                      actions: &lt;Widget&gt;[
                                        // usually buttons at the bottom of the dialog
                                        new FlatButton(
                                          child: new Text("OK"),
                                          onPressed: () {
                                            Navigator.pop(context);
                                          },
                                        ),
                                      ],
                                    );
                                  },
                                );
  
                                Navigator.pop(context);
  
                                setState(() {
                                  isLoading = false;
                                });
                              }).catchError((e) =&gt; print(e));
                            },
                            child: new Container(
                              padding: const EdgeInsets.symmetric(
                                vertical: 20.0,
                                horizontal: 20.0,
                              ),
                              child: new Row(
                                mainAxisAlignment: MainAxisAlignment.center,
                                children: &lt;Widget&gt;[
                                  new Expanded(
                                    child: Text(
                                      "FORGOT PASSWORD",
                                      textAlign: TextAlign.center,
                                      style: TextStyle(
                                          color: Colors.white,
                                          fontWeight: FontWeight.bold),
                                    ),
                                  ),
                                ],
                              ),
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                ],
              )));
    }
  }
  </code></pre>