弹框里面可滚动

    showDialog<void>(
        context: context,
        barrierDismissible: true,
        builder: (context){
          return Dialog(
            child: Container(
              height: my_height * 60,
              child: Column(
                children: <Widget>[
                  Container(
                    height: (my_height * 60) - 70,
                    padding: EdgeInsets.only(top : 15.0, bottom: 15, right: 25, left : 25) ,
                    child: ListView(
                      children: <Widget>[         
                      ],
                    ),
                  ),
                  Container(
                    height: 40,
                    width: my_width * 90,
                    margin : EdgeInsets.only(right : 25 , left:  25, top: 15),
                    decoration: BoxDecoration(
                       color: Colors.blue,
                       borderRadius: BorderRadius.circular(50),
                    ),
                    child: FlatButton(
                        onPressed: (){
                          Navigator.pop(context); //  点击返回上一级
                        },
                        child:  new Text("关闭", style: TextStyle(color: Colors.white),)
                    ),
                  )
                ],
              ),
            ),
          );
        },
    );