customDialog.dart

showDialog(
              context: context,
              builder: (BuildContext context) {
                return AlertDialog(
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(25.0),
                  ),
                  title: Text("Title", textAlign: TextAlign.center),
                  content: Text("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean in congue nisi. Morbi tincidunt est id nibh dapibus, non pulvinar sem sollicitudin. Duis libero quam, posuere non justo non, facilisis sodales elit. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Aliquam sit amet dolor ut sem lobortis commodo id et nunc.", textAlign: TextAlign.center),
                  actions: <Widget>[
                    Container(
                        height: 50,
                        width: 280,
                        child: Row(
                            children: <Widget>[
                              Expanded(
                                  child: Padding(
                                    padding: const EdgeInsets.all(8.0),
                                    child: FlatButton(
                                      onPressed: (){
                                        Navigator.of(context).pop();
                                      },
                                      child: Text("Close"),
                                      shape: RoundedRectangleBorder(
                                          borderRadius: BorderRadius.circular(18.0),
                                          side: BorderSide(color: Theme.of(context).primaryColor)
                                      ),
                                    ),
                                  )
                              ),
                              Expanded(
                                child:Padding(
                                  padding: const EdgeInsets.all(8.0),
                                  child:
                                  FlatButton(
                                    onPressed: (){
                                      Navigator.of(context).pop();
                                    },
                                    child: Text("Help"),
                                    color: Theme.of(context).primaryColor,
                                    shape: RoundedRectangleBorder(
                                      borderRadius: BorderRadius.circular(18.0),
                                    ),
                                  ),
                                ),
                              )

                            ]
                        )
                    )
                  ],
                );
              },
            );