QFileDialog::selectFile doesn't work in native file dialog after switching from non-native one

'QFileDialog::selectFile()' does not pre-fill the given file name in the native file dialog if the dialog has previously been a non-native one, e.g. for this simplified example:

#include <QApplication>
#include <QFileDialog>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QFileDialog fileDialog;
    fileDialog.setOption(QFileDialog::DontUseNativeDialog);
    fileDialog.setOption(QFileDialog::DontUseNativeDialog, false);
    fileDialog.selectFile("test.txt");
    fileDialog.exec();

    return a.exec();
}

When executing this example on KDE Plasma 5, no text is pre-filled in the "Name" textbox.

Expected result: The text "test.txt" should be pre-selected for the file name. It does work as expected when leaving out the 'fileDialog.setOption()' calls.

As far as I can see, the problem is that the call to 'd->usingWidgets()' inside 'QFileDialog::selectFile' (s. [1]) returns true because 'qFileDialogUi' has previously been initialized in the call to 'QFileDialog::setOption(QFileDialog::DontUseNativeDialog)'.

[1] https://codereview.qt-project.org/gitweb?p=qt/qtbase.git;a=blob;f=src/widgets/dialogs/qfiledialog.cpp;h=eb3479b3e0ef1753bcf7215b377263127398da90;hb=481db443d502c8ebc169b7256cb696428cf02199#l1070