Qt app on Mac deactivates when user closes a modal dialog...

(Although I ran into it with 5.2.1, the problem probably exists in prior 5.x versions as well)

When user closes a modal dialog, the application should not get an ApplicationStateChange. Yet on Mac, we do - the application would get deactivated then immediately reactivated again.

Such an unexpected behavior has the potential to throw any code that relies on QGuiApplication::applicationStateChanged() to detect user switching away to another application into a tailspin.

Attached please find a sample app that repros the problem (file listings below).

Here are the steps:
1) launch the sample app
2) select "Test" from the menu bar, then "Random Dialog...", which just launches a modal generic QDialog
3) dismiss the dialog by clicking the red 'Close' button
4) notice that just by closing we get a pair of Qt::ApplicationInactive/Qt::ApplicationActive in the stdout

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QMenuBar* menuBar = new QMenuBar;
    QMenu* testMenu = menuBar->addMenu("Test");
    QAction* act = testMenu->addAction("Random Dialog...");
    connect(act, &QAction::triggered, this, &MainWindow::showRandomDialog);

    setMenuBar(menuBar);

    connect(qApp, &QGuiApplication::applicationStateChanged, this, &MainWindow::handleApplicationStateChanged);
}

MainWindow::~MainWindow()
{
    delete ui;
}


void
MainWindow::handleApplicationStateChanged(Qt::ApplicationState state)
{
    qDebug("App state changed to %d", (int) state);
}

void
MainWindow::showRandomDialog()
{
    QDialog dlg;
    dlg.exec();
}