System tray icon places balloon messages in the wrong location unless process events has been called on Linux

#include <QtGui>

int main(int argc, char **argv) {
    QApplication app(argc, argv);

    QSystemTrayIcon icon;

    QPixmap pm(24, 24);
    pm.fill(Qt::red);
    icon.setIcon(pm);
    icon.show();

    // QApplication.processEvents(); <- this makes it work...
    icon.showMessage("Test", "Am I in the wrong place?");

    app.exec();
}