//Show a form for adding a new category.
        private void btnAddWCategory_Click(object sender, RoutedEventArgs e)
        {
            AddWordsCategory form = new AddWordsCategory(_proxy);

            form.ShowDialog();
            btnWordsCategoriesAct_Click(null, null);
        }
        //Show a form for editting category.
        private void btnEditWCategory_Click(object sender, RoutedEventArgs e)
        {
            int id = Convert.ToInt32((sender as Button).Tag);
            AddWordsCategory form = new AddWordsCategory(_proxy, id);

            form.ShowDialog();
            btnWordsCategoriesAct_Click(null, null);
        }