VolumeSlider’s tooltip misbehaviour

I was developing a Qt application that makes use of a Phonon::VolumeSlider object. But after clicking the mute button beside of the VolumeSlider and verifying its tooltip, I noticed it was showing the wrong volume. A video can explain this better than me:

//www.youtube.com/watch?v=rJcqZ2SVTK0

If you want to reproduce this problem, you can download its source code as a Qt Creator project. Please keep in mind that it’s the source code with errors!  But there’s a workaround to this problem:

1. In the class where you create the Phonon::AudioOutput whose volume is handled by the VolumeSlider, put this:

connect(audioOutput, SIGNAL(mutedChanged(bool)), this, SLOT(handleMute(bool)));
connect(audioOutput, SIGNAL(volumeChanged(qreal)), this, SLOT(handleVolume(qreal)));

2. Create the slots you used above using the following code:

void MainWindow::handleMute(bool mute) {
    if (!mute) {
        audioOutput->setVolume(outputVolume);
    }
}
void MainWindow::handleVolume(qreal volume) {
    outputVolume = volume;
}

3. Declare the slots and the outputVolume variable in your header file:

private:
    qreal outputVolume;

private slots:
    void handleMute(bool mute);
    void handleVolume(qreal volume);

You can download the fixed source code. I don’t know if this behaviour is the expected in Qt, but I filed a bug for it.