JavaScript

Builds 1748 and later support partial .update(). You can use it to add a sliding separator:

var slidingTimeout = null;

function showCurrentTime() {
  slidingTimeout = setInterval(function() {
    dp.update({
      separators: [{color:"Red", location: new DayPilot.Date()}]
    });
  }, 60000);  // once per minute
}

function hideCurrentTime() {
  dp.update({
    separators: []
  });
  clearInterval(slidingTimeout);
}