code: function timePosition(day, time) { // both date objects. day holds 00:00 of current day
  		day = cloneDate(day, true);
  		if (time < addMinutes(cloneDate(day), minMinute)) {
  			return 0;
  		}
  		if (time >= addMinutes(cloneDate(day), maxMinute)) {
  			return slotTable.height();
  		}
  		var slotMinutes = opt('slotMinutes'),
  			minutes = time.getHours()*60 + time.getMinutes() - minMinute,
  			slotI = Math.floor(minutes / slotMinutes),
  			slotTop = slotTopCache[slotI];
  		if (slotTop === undefined) {
  			slotTop = slotTopCache[slotI] =
  				slotTable.find('tr').eq(slotI).find('td div')[0].offsetTop;
  				// .eq() is faster than ":eq()" selector
  				// [0].offsetTop is faster than .position().top (do we really need this optimization?)
  				// a better optimization would be to cache all these divs
  		}
  		return Math.max(0, Math.round(
  			slotTop - 1 + slotHeight * ((minutes % slotMinutes) / slotMinutes)
  		));
  	}
docs: get the Y coordinate of the given time on the given day (both Date objects)