Qt5 OpenFileDialog behaves strange on Gnome3 - c++

Question

I am trying to get a file path at my Qt project. When I was using KDE4 and Qt 4.8 everything worked fine but now I updated to Qt 5 and Gnome 3. And the QFileDialog now looks like this:
Or even like this:
But more often it looks like this:
I noticed the behaviour changes depending on the path being passed as the initial path for the dialog. E. g., if I call
QString path = QFileDialog::getOpenFileName(qobject_cast<QWidget*>(this->parent()), tr("Choose model"), QCoreApplication::applicationDirPath(), QLatin1String("*.obj"));
then I get the second case screenshot.
Yet, if I call
QString path = QFileDialog::getOpenFileName(qobject_cast<QWidget*>(this->parent()), tr("Choose model"), QString(), QLatin1String("*.obj"));
then I get any folder empty while it is not (the first case screenshot).
Also, using this hint, I managed that commenting one line at my ~/.gtkrc-2.0 file and changing the theme to ambiance instead of adwaita at gnome-tweak-tool makes my application show the second-case screenshot.
I use this code to show up the dialog:
QString path = QFileDialog::getOpenFileName(qobject_cast<QWidget*>(this->parent()), tr("Choose model"), QCoreApplication::applicationDirPath(), QLatin1String("*.obj"));
Here, this points to the QGraphicsScene ancestor, OpenGLScene. Here is the code where I create one:
int main(int argc, char **argv)
{
QApplication app(argc, argv);
GraphicsView view;
view.setViewport(new QGLWidget(QGLFormat(QGL::SampleBuffers)));
view.setViewportUpdateMode(QGraphicsView::FullViewportUpdate);
view.setScene(new OpenGLScene);
view.show();
view.resize(1024, 768);
return app.exec();
}