private void MenuItem_Click_add(object sender, RoutedEventArgs e)
        {
            AddTraineeWindow addTraineeWindow = new AddTraineeWindow();

            addTraineeWindow.ShowDialog();
        }
        private void PbAddTrainee_Click(object sender, RoutedEventArgs e)
        {
            AddTraineeWindow addTraineeWindow = new AddTraineeWindow();

            addTraineeWindow.ShowDialog();
        }