success=EyelinkDoDriftCorrection(el [, x][, y][, draw][, allowsetup])
DO PRE-TRIAL DRIFT CORRECTION
We repeat if ESC key pressed to do setup.
Setup might also have erased any pre-drawn graphics.
Note that EyelinkDoDriftCorrection() internally uses Beeper() and Snd() to play
auditory feedback tones if el.targetbeep=1 or el.feedbackbeep=1 and the
el.callback function is set to the default PsychEyelinkDispatchCallback().
If you want to use PsychPortAudio in a script that also calls EyelinkDoDriftCorrection,
then read “help Snd” for instructions on how to provide proper interoperation
between PsychPortAudio and the feedback sounds created by Eyelink.