Flutter, How to remove white spaces around dialog box?

Inside AlertDialog set contentPadding 0

contentPadding: EdgeInsets.zero,

make title to have Container, and add

width: MediaQuery.of(context).size.width,

Then give 0 (or what value you want to have for horizontal patting) to insetPadding like this:

insetPadding: EdgeInsets.symmetric(horizontal: 0),

Below is my example show dialog code, contains alertDialog with horizontal padding = 15 :

Future<void> _showLogoutDialog(BuildContext context) async {    return showDialog<void>(      context: context,      barrierDismissible: true,      builder: (BuildContext context) {        return AlertDialog(          titlePadding: EdgeInsets.only(top: 12, left: 24, right: 12),          contentPadding: EdgeInsets.only(top: 12, left: 24, bottom: 20),          insetPadding: EdgeInsets.symmetric(horizontal: 15),          titleTextStyle: TextStyle(            color: ColorStyles.primary_blue500,            fontFamily: 'Muli',            fontWeight: FontWeight.w500,            fontStyle: FontStyle.normal,            fontSize: 16.0,          ),          contentTextStyle: TextStyle(            color: ColorStyles.grey2,            fontFamily: 'Muli',            fontWeight: FontWeight.w400,            fontStyle: FontStyle.normal,            fontSize: 14.0,          ),          title: Container(            width: screenUsableHeight(context),            child: Row(              mainAxisSize: MainAxisSize.max,              mainAxisAlignment: MainAxisAlignment.spaceBetween,              children: [                Text('Log out'),                IconButton(                  icon: Icon(                    Icons.close,                    color: ColorStyles.grey2,                    size: 28,                  ),                  onPressed: () => Navigator.of(context).pop(),                  splashColor: Colors.transparent,                  highlightColor: Colors.transparent,                  tooltip: "close",                )              ],            ),          ),          //EN: Logging out          content: SingleChildScrollView(            child: ListBody(              children: <Widget>[                Text('Do you want to leave?'),              ],            ),          ),          actions: <Widget>[            FlatButton(              child: Text(                'Yes',                style: TextStyle(                  color: ColorStyles.primary_blue500,                  fontFamily: 'Muli',                  fontWeight: FontWeight.w500,                  fontStyle: FontStyle.normal,                  fontSize: 16.0,                ),              ), //EN: Yes              onPressed: () {                _logOut(context);              },            ),            FlatButton(              child: Text(                'No',                style: TextStyle(                  color: ColorStyles.grey2,                  fontFamily: 'Muli',                  fontWeight: FontWeight.w500,                  fontStyle: FontStyle.normal,                  fontSize: 16.0,                ),              ), //EN: No              onPressed: () {                Navigator.of(context).pop();              },            ),          ],        );      },    );  }

This looks like:

display of alert dialog

Don't use AlertDialog at all. Just send bodyProgress to showDialog

showDialog(context: context, builder: (_) => bodyProgress,);