The nearest candidate to (pointerX, pointerY), or null if nothing is
within maxDistancePx — the pointer is in genuinely empty space, not just
closer to one candidate than another. Ties (equal distance) resolve to
whichever candidate appears first, for deterministic behaviour.
The nearest candidate to (pointerX, pointerY), or null if nothing is within maxDistancePx — the pointer is in genuinely empty space, not just closer to one candidate than another. Ties (equal distance) resolve to whichever candidate appears first, for deterministic behaviour.