Problems with threads and windows

[SkripT]

Yes this could cause an error but I made it this way because if you see the example /examples/threads/mandelbrot passes a reference to the generated image too. This is because the connection between the signals and slots is queued because are different threads, as the documentation explains. This means, I think, that the parameters of the signal are copied in a queue before the slot is called. But depending in the time that the parameters are copied in the queue could cause an error, so why an example of the doucmentation are doing it wrong?