private async void CancelButton_Click(object sender, Windows.UI.Xaml.RoutedEventArgs e)
 {
     StartButton.IsEnabled    = false;
     PauseButton.IsEnabled    = false;
     CancelButton.IsEnabled   = false;
     LoadJobsButton.IsEnabled = false;
     AddJobButton.IsEnabled   = false;
     await jobManager.CancelJobs();
 }