title: Fullcalendar add tooltip to events
body: <p>I'm using fullcalendar in my php site. I load events with eventSources, giving it an url redirecting to my php controller, which generates json data. Before the calendar is rendered, I wish every event has a tooltip. To this scope I wrote a javascript function that add the tooltip: </p>
  
  <pre><code> function dailyTooltip(){
     $('.fc-day-grid-event, .fc-time-grid-event').each(function(){
        var content = $(this).data('content');
        $(this).attr('title',''); 
        $(this).tooltip({
         tooltipClass: 'event-tooltip',
         content: content,
        }); 
     });
   }
  </code></pre>
  
  <p>where content is html content. The function runs after calendar rendering.
  After the calendar has been rendered, the tooltip is not showing. </p>
  
  <p>To resolve this problem, I tried to add the function to datesRender, and eventRender. datesRender seems to work, but only when I change view (e.g. from timeGrid to dayMonthGrid). eventRender doesn't work.</p>