Question

Following the the code linked from here: Trap click event on dock icon using Qt on Mac, I tried to call the following method directly in my QApplication’s constructor to receive notification of dock icon click events:

[[NSAppleEventManager sharedAppleEventManager]
     setEventHandler: m_dockIconClickEventHandler
     andSelector: @selector(handleDockClickEvent:withReplyEvent:)
     forEventClass: kCoreEventClass
     andEventID: kAEReopenApplication];

If I call it directly, I do not receive notifications of this event. However, if I call it using QTimer::singleShot with a delay of, say, 5000 ms, I receive the notifications just fine.

Also, according to the Qt documentation, “A QTimer with a timeout interval of 0 will time out as soon as all the events in the window system’s event queue have been processed.” So I tried 0 ms, but that didn’t work. 1 or above seems to.

Why do I need to wait and what is a better way to handle this situation than delaying for n ms?

Answer 1

When your application exec() is called, Qt sets its own event handlers, so your handler is overriden.
You may use in your constructor

connect(this, SIGNAL(setupDockEventMonitor()), SLOT(onSetupDockEventMonitor()), Qt::QueuedConnection);
emit setupDockEventMonitor();

And in onSetupDockEventMonitor() do install this event handler.