#include <QtGui/QApplication>
#include <QtGui/QWidget>
#include <QtCore/QDebug>
#include <QtCore/QTimer>
#include <QtCore/QThread>
#include <QtCore/QMutex>
#include <QtCore/QQueue>

class MyThread : public QThread
{
    Q_OBJECT
public:
    MyThread(QObject *parent)
        : QThread(parent)
    {
    }

public slots:
    void emitSignal1()
    {
        mutex.lock();
        signalQueue << 1;
        mutex.unlock();
    }

    void emitSignal2()
    {
        mutex.lock();
        signalQueue << 2;
        mutex.unlock();
    }

signals:
    void sig1();
    void sig2();

protected:
    void run()
    {
        while (true) {
            mutex.lock();
            unsigned char s = 0;
            if (!signalQueue.isEmpty())
                s = signalQueue.dequeue();            
            mutex.unlock();

            switch (s) {
                case 1:
                    emit sig1();
                    break;
                case 2:
                    emit sig2();
                    break;
            }
        }
    }

    QMutex mutex;
    QQueue<uchar> signalQueue;
};

class MyWindow : public QWidget
{
    Q_OBJECT
public:
    MyWindow()
    {
        MyThread* t = new MyThread(this);
        connect(t, SIGNAL(sig1()), this, SLOT(onSig1()));
        connect(t, SIGNAL(sig2()), this, SLOT(onSig2()));
        t->start();

        // post event before the event loop starts
        t->emitSignal1();

        // post event after the event loop has started
        QTimer::singleShot(0, t, SLOT(emitSignal2()));
    }

public slots:
    void onSig1()
    {
        qDebug("--- onSig1()");
    }

    void onSig2()
    {
        qDebug("--- onSig2()");
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MyWindow w;
    w.showMaximized();
    return a.exec();
}

#include "main.moc"