StateObject类的引用空间是什么？

Question

StateObject类的引用空间是什么，在前面已经写了using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;
网上查了说这是自定义类？

Answer 1

http://bbs.csdn.net/topics/390044457