Clicking on QMacToolBar does not close open QMenus

#include <QApplication>
#include <QMacToolBar>
#include <QMacToolBarItem>
#include <QStackedLayout>
#include <QtWidgets>

// A Widget with a stacked layout containing
//  1) a widget coloured in cyan
//  2) a widget with a pushbutton that opens a menu on click.
class MyWidget : public QWidget
{
public:
    MyWidget( QWidget * inParent ) : QWidget( inParent )
    {
        mStackLayout = new QStackedLayout();

        // first Stack Entry
        auto firstWidget = new QWidget( this );
        firstWidget->setFixedSize( QSize{ 200, 100 } );
        firstWidget->setStyleSheet( "background-color:cyan" );

        // second Stack Entry
        auto secondWidget = new QPushButton( "Actions", this );
        auto menu = new QMenu( secondWidget );
        menu->addAction( "Action1" );
        menu->addAction( "Action2" );
        secondWidget->setMenu( menu );        mStackLayout->addWidget( firstWidget );
        mStackLayout->addWidget( secondWidget );
    }

    void SwitchToTab( int index )
    {
        mStackLayout->setCurrentIndex( index );
    }
private:
    QStackedLayout * mStackLayout;
};

// A MainWindow that has a QMacToolBar that controls the widget being
// visible in MyWidget
class MainWindow : public QMainWindow
{
public:
    MainWindow(QWidget *parent = nullptr)
        : QMainWindow(parent)
    {
        auto toolBar = new QMacToolBar( this );
        auto centralWidget = new MyWidget(this);
        setCentralWidget( centralWidget );
        auto firstItem = toolBar->addItem( QIcon( QPixmap( "/Users/Stack1.png" ) ), "Stack1" ); // image missing, but that shouldn't matter
        firstItem->setSelectable( true );
        connect
        (
            firstItem,
            &QMacToolBarItem::activated,
            [  centralWidget ]
            {
                centralWidget->SwitchToTab( 0 );
            }
        );
        auto secondItem = toolBar->addItem( QIcon( QPixmap( "/Users/Stack2.png" ) ), "Stack2" ); // image missing, but that shouldn't matter
        secondItem->setSelectable( true );
        connect
        (
            secondItem,
            &QMacToolBarItem::activated,
            [  centralWidget ]
            {
                centralWidget->SwitchToTab( 1 );
            }
        );
        window()->winId();
        toolBar->attachToWindow( window()->windowHandle() );
    }
};


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