wpf 的dispatcher

wpf项目中后台代码调用界面控件时，会提示进程调用的错误。

private Thread JxThread = null;  //定义线程

private DataLoading.Loading nLoadW=new DataLoading.Loading();
        private void ShowMessage()                                                 //要让主线程完成的事情
        {

nLoadW.Dispatcher.BeginInvoke(new Action(() =>
            {
                nLoadW.Left = MWLeft;
                nLoadW.Top = MWTop;
                nLoadW.Show();
            }));

System.Windows.Threading.Dispatcher.Run();
        }