if (filename.isEmpty())
    {
         filename = QFileDialog::getSaveFileName(this,tr("Zapisz plik jako..."),tr("/home/"),tr("Pliki tekstowe (*.txt)"));

         text_z_pola += ui -> textEdit -> toPlainText();
         text_z_pola += " ";
         text_z_pola += ui -> textEdit_2 ->toPlainText();

         ui -> label_2 ->setText(text_z_pola);

         do_pliku();
    }
    else
    {
        text_z_pola += ui -> textEdit -> toPlainText();
        text_z_pola += " ";
        text_z_pola += ui -> textEdit_2 ->toPlainText();


        ui -> label_2 ->setText(text_z_pola);

        do_pliku();
    }