title: Force QFileDialog::DontUseNativeDialog globally in a QT program
body: <p>To avoid the freeze at <a href="https://bugreports.qt.io/browse/QTBUG-59184" rel="nofollow noreferrer">https://bugreports.qt.io/browse/QTBUG-59184</a> on Ubuntu Unity (and some networking issues on Windows), I'd like to force <code>QFileDialog::DontUseNativeDialog</code> in all the calls to the static functions of <code>QFileDialog</code>. Some of the calls come from third party libraries, thus it is not easy to change them individually in code, so instead I'd prefer to set some flag to the <code>QApplication</code> (or other means) that will apply to all those calls to QFileDialog.</p>