DBus QSystemTrayIcon does not work or causes crash

#include <QApplication>
#include <QSystemTrayIcon>
#include <QMenu>
#include <QDebug>
#include <QTimer>

class Handler : public QObject
{
    Q_OBJECT

public slots:
    void trigger()
    {
        qDebug() << "Triggered";
    }

    void setupMenu()
    {
        menu.clear();

        QAction *action1 = menu.addAction("Debug output: Triggered");
        connect(action1, SIGNAL(triggered()), SLOT(trigger()));

        QAction *action2 = menu.addAction("Re-setup menu");
        connect(action2, SIGNAL(triggered()), SLOT(setupMenu()));

        menu.addAction(QString::number(rand()));
    }

public:
    QMenu menu;
};

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

    QSystemTrayIcon tray;
    Handler h;

    tray.setContextMenu(&h.menu);
    tray.show();
    h.setupMenu();

    return a.exec();
}

#include "main.moc"