title: How to design Custom dialog box using close icon with flutter?
body: <p>I have an image of the dialog box and trying to design the same as below the image.  </p>
  
  <p><a href="https://i.stack.imgur.com/u6hfI.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/u6hfI.jpg" alt="enter image description here"></a></p>
  
  <p>I tried but it's not same as above the image
  I just want set cross button at the top right corner, like above the image.
  i used Stack, and a placed <code>Positioned</code> widget at the <code>top:0.0</code>,<code>right:0.0</code>.</p>
  
  <p>CODE:</p>
  
  <pre><code> customDialogBox(BuildContext context) {
      return showDialog(
          context: context,
          builder: (BuildContext context) {
            return AlertDialog(
              backgroundColor: Colors.red,
              shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.all(Radius.circular(32.0))),
              contentPadding: EdgeInsets.only(top: 10.0),
              content: Stack(
                children: &lt;Widget&gt;[
                  Container(
                width: MediaQuery.of(context).size.width,
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  mainAxisSize: MainAxisSize.min,
                  children: &lt;Widget&gt;[
                    SizedBox(
                      height: 20.0,
                    ),
                    Center(
                      child: Padding(
                        padding: const EdgeInsets.all(10.0),
                        child: new Text("Sorry please try \n again tomorrow", style:TextStyle(fontSize: 30.0,color: Colors.white)),
                      )//
                    ),
  
                    SizedBox(
                      height: 20.0,
                      width: 5.0,
                    ),
                    Divider(
                      color: Colors.grey,
                      height: 4.0,
                    ),
  
                   InkWell(
                      child: Container(
                        padding: EdgeInsets.only(top: 15.0, bottom: 15.0),
                        decoration: BoxDecoration(
                          color:Colors.white,
                          borderRadius: BorderRadius.only(
                          bottomLeft: Radius.circular(32.0),
                          bottomRight: Radius.circular(32.0)),
                        ),
                        child:  Text(
                         "OK",
                          style: TextStyle(color: Colors.blue,fontSize: 25.0),
                          textAlign: TextAlign.center,
                        ),
                      ),
                      onTap:(){
                        Navigator.pop(context);
                      },
                    ),
                  ],
                ),
              ),
              Positioned(
                top: 0.0,
                right: 0.0,
                child: FloatingActionButton(
                  child: Image.asset("assets/red_cross.png"),
                  onPressed: (){
                  Navigator.pop(context);
                  },
                  shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(80)),
                  backgroundColor: Colors.white,
                  mini: true,
                  elevation: 5.0,
                ),
              ),
            ],
          )
        );
      });
    }
  </code></pre>
  
  <p>here's my Dialog Box:
  <a href="https://i.stack.imgur.com/QUJQO.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/QUJQO.jpg" alt="enter image description here"></a></p>