void MainWindow::onProducerChanged()
{
    MLT.refreshConsumer();
    if (playlist() && MLT.producer() && MLT.producer()->is_valid()
        && MLT.producer()->get_int(kPlaylistIndexProperty))
        m_playlistDock->setUpdateButtonEnabled(true);
}
void MainWindow::onProducerChanged()
{
    MLT.refreshConsumer();
    if (playlist() && MLT.producer() && MLT.producer()->is_valid()
        && MLT.producer()->get_int(kPlaylistIndexProperty))
        m_playlistDock->setUpdateButtonEnabled(true);
}