open QFileDialog resets window title of calling dialog window

Usualy I leave the main window title as it is. After application startup I set the title to some string like so

// ...
ui->setupUi(this);
this->setWindowTitle("some useless window title");
// ...

Now I have a button or menu with the triggered oder click action opens a QFileDialog:

QString filename = QFileDialog::getOpenFileName(this, tr("Open file"));

At the moment this happens, the title of the mainwindow is resetted to its default value!
Is this a bug?