These docs are for an old release.
Info on upgrading to version 2/3
eventDragStart
Triggered when event dragging begins.
function( event, jsEvent, ui, view ) { }
event
is an Event Object that hold the event’s information (date, title, etc).
jsEvent
holds the native javascript event with low-level information such as click coordinates.
ui
holds the jQuery UI object.
view
holds the current View Object.