can the Open File dialog be used to select a Folder?

You can try this one:

QString QFileDialog::getExistingDirectory ( QWidget * parent = 0, const QString & caption = QString(), const QString & dir = QString(), Options options = ShowDirsOnly ) [static]

This one is used to choose a directory, and will popup a dialog like you show at last.

Demo:

 QString dir = QFileDialog::getExistingDirectory(this, tr("Open Directory"),
                                             "/home",
                                             QFileDialog::ShowDirsOnly
                                             | QFileDialog::DontResolveSymlinks);