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>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap-theme.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<div style="border:solid 2px red;">
        <div id='calendar'></div>
        <button type="button" class="btn btn-primary" data-toggle="collapse" data-target="#demo">
                Horizontal Collapsible
            </button>
            <div id="demo" class="collapse in width" style="background-color:yellow;float:right;border:1px solid black;margin-top:-10em;opacity:1;z-index:5000;">
                <div style="padding: 20px; overflow:hidden; width:300px;">
                    Here is my content
                </div>
            </div>
</div>

CSS

#demo.width {
        height: auto;
        -webkit-transition: width 0.35s ease;
        -moz-transition: width 0.35s ease;
        -o-transition: width 0.35s ease;
        transition: width 0.35s ease;
    }

JavaScript

$(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);
        }
    });
});