Same problem here, especially with the corners of the screen! The offset seems to be more or less constant, even if I repeat the calibration process multiple times. Usually the gaze point is shifted to the center of the screen, with the effect being more noticeable at the edges. Could this be related to my astigmatism?
Either way: being able to tune the existing calibration settings the way Davel proposed would be neat.
(Click one of the 9 areas -> visualization is disabled -> look at the area’s center -> have visualization reflect the change -> repeat until you get it right)
But maybe (since tracking works fine in any part of the screen for my healthy-eyed girlfriend) this problem is specific to me or my glasses. An option to manually offset the gaze point as a last resort workaround would be great in that case.
(Click one of the 9 areas -> use arrow keys to set offset for that region)