private static void listBox_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
 {
     // notify the helper class that the list box has terminated the drag click
     DragSelectionHelper.SetIsDragClickStarted(DragSelectionHelper.ListBox, false);
 }
 private static void listBox_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
 {
     // notify the helper class that the listbox has initiated the drag click
     DragSelectionHelper.SetIsDragClickStarted(DragSelectionHelper.ListBox, true);
 }