Qt Showing nothing

void MainWindow::dropEvent(QDropEvent * event)
{
    event->acceptProposedAction();

    const QMimeData * mimeData = event->mimeData();

    // check for our needed mime type, here a file or a list of files
    if (mimeData->hasUrls())
    {
        QList<QUrl> urlList(mimeData->urls());
        QString fileName;
        bool encrypted;

        // extract the local paths of the files
        for (int i = 0; i < urlList.size() && i < 32; ++i)
        {
            fileName = urlList.at(i).toLocalFile();

            // Initialisation de la fenêtre de chargement
            this->tmpWin = new QWidget;
            QVBoxLayout * vLayout = new QVBoxLayout;
            QLabel * txtLabel = new QLabel(tr("Processing..."));
            QProgressBar * pBar = new QProgressBar;

            pBar->setRange(0, 0);
            vLayout->addWidget(txtLabel, 0, Qt::AlignHCenter);
            vLayout->addWidget(pBar, 0, Qt::AlignHCenter);

            //this->tmpWin->setAttribute(Qt::WA_DeleteOnClose);
            this->tmpWin->setLayout(vLayout);
            this->tmpWin->setWindowFlags(Qt::SplashScreen);
            // ---

            if ( fileName.contains(QRegExp(APPCRYPTEXT+"$")) )
            {
                this->tmpWin->show();
                qApp->processEvents();    // I tried this line
                this->tmpWin->update(); // and/or this line
                this->db->decryptFile(fileName);
                this->tmpWin->hide();
            }
            else
            {
                this->tmpWin->show();
                qApp->processEvents();    // I tried this line
                this->tmpWin->update(); // and/or this line
                this->db->encryptFile(fileName);
                this->tmpWin->hide();
            }
        }

        this->tray->showMessage(tr("Finished !"), tr("I've finished encrypting or decrypting (whatever it was)\nyour files..."), QSystemTrayIcon::Information, 2000);
    }
}