Tune the playhead accuracy so that notes sound when the playhead hits them

hi, the note that plays on row 24 starts visually playing when the playhead is on row 23. maybe the playhead visualisation could be tweaked by +1 so that it feels more accurate?
<img width="1201" alt="image" src="https://user-images.githubusercontent.com/4966687/63653373-8dc2d300-c774-11e9-8082-d08259672e11.png">
