private void DeleteQuestion_Click(object sender, RoutedEventArgs e)
{
if (listBox.SelectedItem != null)
{
_contentManager.DeleteQuestion((listBox.SelectedItem as Question).ID, _selectedQuiz);
questions.Remove(listBox.SelectedItem as Question);
EditQuestion.IsEnabled = false;
DeleteQuestion.IsEnabled = false;
_saved = false;
Save.IsEnabled = true;
}
}