private void NewPlaylistButton_Click(object sender, RoutedEventArgs e)
        {
            NewPlaylistForm newPlaylistForm = new NewPlaylistForm();

            newPlaylistForm.NewNameTextBox.Focus();
            bool?result = newPlaylistForm.ShowDialog();

            if (result == true)
            {
                musicLib.AddPlaylist(newPlaylistForm.NewNameTextBox.Text);
                SetupPlaylistList();
            }
        }
        private void RenameMenuItem_Click(object sender, RoutedEventArgs e)
        {
            NewPlaylistForm newPlaylistForm = new NewPlaylistForm();

            newPlaylistForm.NewNameTextBox.Text = PlaylistList.SelectedItem.ToString();
            newPlaylistForm.NewNameTextBox.Focus();
            newPlaylistForm.NewNameTextBox.SelectAll();
            bool?result = newPlaylistForm.ShowDialog();

            if (result == true)
            {
                musicLib.RenamePlaylist(PlaylistList.SelectedItem.ToString(), newPlaylistForm.NewNameTextBox.Text);
                SetupPlaylistList();
            }
        }