Thanks again for your reply.

Please see the attached code. The outputs are from two scenarios/tests. The first one does NOT call processEvents(). The second one does.

There is only one connection and it is called once. If you run the code in Windows 7 you will see the problem easily,

This is not an issue of multiple calls to connect.

As I debug further, I can extrapolate that that because the sleep takes too long, the signal is resent/requeued. If processEvents() (scenario #2) is called after the timeout, then the signal is processed inline. I would suggest that the QT signal processor is not removing the signal before it is processed. Therefore, in scenario #2 it is processed again (as it is still pending).