Future<void> _showAlertDialog() async {
    return showDialog<void>(
      context: context,
      barrierDismissible: false,
      builder: (BuildContext context) {
        return AlertDialog(
          title: Text('Veniam laboriosam alias'),
          content: SingleChildScrollView(
            child: ListBody(
              children: <Widget>[
                Text('Lorem ipsum dolor sit amet consectetur adipisicing elit. Minus fuga excepturi nisi dolores reprehenderit officia rerum porro.'),
              ],
            ),
          ),
          actions: <Widget>[
            FlatButton(
              child: new Text("Avbryt", style: TextStyle(fontSize: 18)),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
            FlatButton(
              child: new Text("Ja", style: TextStyle(fontSize: 18)),
              onPressed: () {
                // Gå vidare
              },
            ),
          ],
        );
      },
    );
  }

FlatButton(
    child: Text('Klicka här'),
    onPressed: () {
    _showAlertDialog();
    },
),