public void ChangeFormExecuted(object sender, ExecutedRoutedEventArgs e)
        {
            var f = new AddChangeSynWindow("Изменение формы слова", "Форма:", _selectedSynonym, _selectedWordForm, false);

            if (f.ShowDialog() != true)
            {
                return;
            }
            try
            {
                _namedNode.ChangeWordForm(_selectedSynonym, _selectedWordForm, f.NewWord);
                SetDataContext();
            }
            catch (ArgumentException ex)
            {
                MessageBox.Show(ex.Message);
            }
        }