When using the code below then with Qt 4.4.2 the files are listed, but with 4.5.2 they are not. It seems as if the part (details) confuses the search algorithm.

QString file = QFileDialog::getOpenFileName(this, "Datei öffnen", "", "My
file type (details) (*.Z9A)");

If it is not supported to have the (details) part in the example above, then this should be clarified in the documentation for setNameFilter()

http://doc.trolltech.com/4.5/qfiledialog.html#setNameFilter