FullCalendar was initially designed without much notion of timezones. By default, it ignores timezone offsets in the dates it receives.
The original assumption was that if you received a date from Brussels, say "2013-09-01T12:00:00+02:00"
, which is noon, it would display as noon in every timezone.
However, FullCalendar shoehorns this value into a local date. With the same example, if you were in San Francisco, it internally stores the date as "2013-09-01T12:00:00-08:00"
. This is bad for two reasons: