public partial class MainWindow : Window, INotifyPropertyChanged
        {
            private readonly BackgroundWorker worker = new BackgroundWorker();
            public MainWindow()
            {
                InitializeComponent();
                worker.WorkerReportsProgress = true;
                worker.WorkerSupportsCancellation = true;
                worker.DoWork += myWorker_DoWork;
                worker.RunWorkerCompleted += myWorker_RunWorkerCompleted;
              
                DataContext = this;
            }
           
            private int num = 10;
            public int Num
            {
    
                get { return num; }
                set { num = value; OnPropertyChanged("Num"); }
            }
            void myWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
            {
                   
            }
            void myWorker_DoWork(object sender, DoWorkEventArgs e)
            {
                for (int i = 0; i < 6; i++)
                {
                    System.Threading.Thread.Sleep(1000);
                    worker.ReportProgress(i * 10);
                    Num++;
                }
                
               
            }
            private void btn1_Click(object sender, RoutedEventArgs e)
            {
                worker.RunWorkerAsync();
            }
            private void dispatcherTimer_Tick(object sender, EventArgs e)
            {
                Num--;
                lb1.Items.Add(Num);
                CommandManager.InvalidateRequerySuggested();
                lb1.Items.MoveCurrentToLast();
                lb1.SelectedItem = lb1.Items.CurrentItem;
                lb1.ScrollIntoView(lb1.Items.CurrentItem);
                
            }
    
            private void btn_Click(object sender, RoutedEventArgs e)
            {
                System.Windows.Threading.DispatcherTimer dispatcherTimer = new System.Windows.Threading.DispatcherTimer();
                dispatcherTimer.Tick += new EventHandler(dispatcherTimer_Tick);
                dispatcherTimer.Interval = new TimeSpan(0, 0, 1);
                dispatcherTimer.Start();
            }
            public event PropertyChangedEventHandler PropertyChanged;
            protected void OnPropertyChanged([System.Runtime.CompilerServices.CallerMemberName] string name = null)
            {
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
            }
    
        }