FullCalendar: Event with tooltips/custom event attributes

HTML

<link rel="stylesheet" href="http://arshaw.com/js/fullcalendar-1.5.3/fullcalendar/fullcalendar.css">
<script src="http://www.arshaw.com/js/fullcalendar-1.5.3/fullcalendar/fullcalendar.min.js"></script>
<script src="http://davis-design.de/marktadresse/layout/js/foundation-datapicker.js"></script>
<link rel="stylesheet" href="http://davis-design.de/marktadresse/layout/css/foundation-datapicker.css">
</br>

Datepicker :
<input type="text" id="endDate" name="end_datum" class="input_text" value="">
</br>
</br>
</br>
</br>

<div style="border:solid 2px red;">
  <div id='calendar'></div>
</div>
<div class="tag hide" id="cal-info">

</div>

CSS

.tag {
	  background-color: #000;
	  color: #fff;
	  padding: 3px;
	  max-height: 60px;
	  overflow: visible;
	  position: fixed;
	  z-index: 999;
	}
	
	.tag:after {
	  content: "";
	  border-top: 16px solid red;
	  border-left: 8px solid transparent;
	  border-right: 8px solid transparent;
	  position: absolute;
	  bottom: -16px;
	  left: calc(50% - 8px);
	}
	
	.fc-border-separate thead.sticky {
	  width: 100%;
	  position: fixed;
	  top: 0px;
	  left: 0px;
	  display: table;
	  background: #fff;
	}

JavaScript

var nowTemp = new Date();
	var now = new Date(nowTemp.getFullYear(), nowTemp.getMonth(), nowTemp.getDate(), 0, 0, 0, 0);
	var checkin = jQuery('#startDate').fdatepicker({
	  format: "dd.mm.yyyy",
	}).data('datepicker');
	var checkout = jQuery('#endDate').fdatepicker({
	  format: "dd.mm.yyyy",
	}).on('changeDate', function(ev) {
	  var startDate = new Date(ev.date);
	  $('#calendar').fullCalendar('gotoDate', startDate);
	}).data('datepicker');




	$(document).ready(function() {

	  var date = new Date();
	  var d = date.getDate();
	  var m = date.getMonth();
	  var y = date.getFullYear();

	  var events_array = [{
	    title: 'Test1',
	    start: new Date(2012, 8, 20),
	    tip: 'Personal tip 1'
	  }, {
	    title: 'Test2',
	    start: new Date(2012, 8, 21),
	    tip: 'Personal tip 2'
	  }];

	  $('#calendar').fullCalendar({
	    header: {
	      left: 'prev,next today',
	      center: 'title',
	      right: 'month,agendaWeek,agendaDay'
	    },
	    selectable: true,
	    events: events_array,
	    eventRender: function(event, element) {
	      element.attr('title', event.tip);
	    }
	  });
	});

	$(".fc-header-left").hide();
	$(".fc-header-right").hide();

	$(window).scroll(function() {
	  if ($(this).scrollTop() > 1) {
	    $('.fc-border-separate thead').addClass("sticky");
	  } else {
	    $('.fc-border-separate thead').removeClass("sticky");
	  }
	});