private void ButtonNew_Click(object sender, EventArgs e)
        {
            var formCreateRepertoire = new RepertoireInfoForm();

            if (formCreateRepertoire.ShowDialog() == DialogResult.OK)
            {
                var newRepertoire = formCreateRepertoire.Repertoire;
                repertoiresListBox.Items.Add(newRepertoire.ToShortString());
                repertoires.Add(newRepertoire.ToShortString(), newRepertoire);
            }
        }
        private void ButtonEditSelected_Click(object sender, EventArgs e)
        {
            if (repertoiresListBox.SelectedIndices.Count > 1)
            {
                MessageBox.Show("Виберіть рівно один репертуар");
                return;
            }
            var selectedItem = repertoiresListBox.SelectedItem;
            var id           = selectedItem.ToString();

            repertoires.TryGetValue(id, out Repertoire selectedRepertoire);
            var formEditRepertoire = new RepertoireInfoForm(selectedRepertoire);

            if (formEditRepertoire.ShowDialog() == DialogResult.OK)
            {
                var editedRepertoire = formEditRepertoire.Repertoire;
                repertoires.Remove(id);
                repertoiresListBox.Items.Remove(id);
                repertoires.Add(editedRepertoire.ToShortString(), editedRepertoire);
                repertoiresListBox.Items.Add(editedRepertoire.ToShortString());
            }
        }