procedure TMainForm.ConnectButtonClick(Sender: TObject);

begin

  ConnectButton.Enabled := false;

  if IdFTP1.Connected then try

    if TransferrignData then IdFTP1.Abort;

    IdFTP1.Quit;

  finally

    CurrentDirEdit.Text := '/';

    DirectoryListBox.Items.Clear;

    SetFunctionButtons(false);

    ConnectButton.Caption := 'Connect';

    ConnectButton.Enabled := true;

    ConnectButton.Default := true;

  end

  else with IdFTP1 do try

    Username := UserIDEdit.Text;

    Password := PasswordEdit.Text;

    Host := FtpServerEdit.Text;

    Connect;                               //<-exception

    Self.ChageDir(CurrentDirEdit.Text);

    SetFunctionButtons(true);

    SaveFTPHostInfo(FtpServerEdit.Text, 'FTPHOST');

  finally

    ConnectButton.Enabled := true;

    if Connected then begin

      ConnectButton.Caption := 'Disconnect';

      ConnectButton.Default := false;

    end;

  end;

end;