Thanks for the suggestions! I'm working on it. 'tis a bit trickier than I expected.

EDIT: Have added a visible cursor now (with the ability to toggle it on or off to preserve the initial feel)! You should see it if you refresh.

Wasn't too complicated in the end, and did some fun calibration target practice with "x"s to make sure it was positioned nicely.

Thanks for the feedback josephcsible and Apreche!