Pumps the Experiment Process Windows Message Queue so the PsychoPy Window does not appear to be ‘dead’ to the OS. If you are not flipping regularly (say because you do not need to and do not want to block frequently, you can call this, which will not block waiting for messages, but only pump out what is in the que already. On an i7 desktop, this call method takes between 10 and 90 usec.