Thread synchronization, QWaitCondition, and recursiveMutex

[jacek]

Not sure about that: does the invokeMethod above with the BlockingQueuedConnection return when the signal has been delivered or when the desired slot has been fully executed?

The blocking is done with a semaphore which is released in QMetaCallEvent destructor, so the sender is blocked as long as the meta call event object exists. AFAIK when event loop picks up the meta call event it first executes the slot and then deletes the event.