public ListStaffpage()
        {
            InitializeComponent();
            ProgressBar_.IsEnabled  = true;
            ProgressBar_.Visibility = Visibility.Visible;

            Thread thread = new Thread(delegate()
            {
                ObservableCollection <Staff> staffs = new ObservableCollection <Staff>();

                staffs = manage.LoadData_Staff();
                Dispatcher.Invoke(() =>
                {
                    liststaff.ItemsSource   = staffs;
                    ProgressBar_.IsEnabled  = false;
                    ProgressBar_.Visibility = Visibility.Hidden;
                });
            });

            thread.Start();
        }