private void buttonDelete_Click(object sender, EventArgs e)
        {
            string message;

            if (listView.SelectedItems.Count == 1)
            {
                message = string.Format(new TermsProvider()["DeleteQuestion"].ToString(), "document");
            }
            else
            {
                message = string.Format(new TermsProvider()["DeleteQuestionSeveral"].ToString(), "documents");
            }
            DialogResult result = MessageBox.Show(message, "Deleting confirmation", MessageBoxButtons.YesNoCancel,
                                                  MessageBoxIcon.Warning, MessageBoxDefaultButton.Button2);

            if (result == DialogResult.Yes)
            {
                try
                {
                    int count = SelectedItems.Count;
                    for (int i = 0; i < count; i++)
                    {
                        task.RemoveDocument(SelectedItems[i]);
                    }
                }
                catch (Exception ex)
                {
                    Program.Provider.Logger.Log("Error while deleting data", ex); return;
                }
                UpdateInformation();
            }
        }