Interaction logic for DownloadTracker.xaml
Inheritance: System.Windows.Controls.UserControl
        void exitScreen_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
        {
            if (exitScreen != null && exitScreen.Visibility != System.Windows.Visibility.Visible)
            {
                MainGrid.Children.Remove(exitScreen);

                if (((ExitScreenVM)exitScreen.DataContext).CarryOnExit)
                {
                    Exit();
                }
                else
                    downloadTracker = null;
            }
        }
        private void Tracker_Button_Click(object sender, RoutedEventArgs e)
        {
            downloadTracker = new DownloadTracker(viewModel.DownloadList);
            downloadTracker.IsVisibleChanged += downloadTracker_IsVisibleChanged;

            MainGrid.Children.Add(downloadTracker);
        }
 void downloadTracker_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
 {
     if (downloadTracker != null && downloadTracker.Visibility != System.Windows.Visibility.Visible)
     {
         MainGrid.Children.Remove(downloadTracker);
         downloadTracker = null;
     }
 }