These docs are for an old release.
Info on upgrading to version 2/3
Requirements
Event dragging and resizing requires the following jQuery UI modules:
These modules can be conveniently bundled/compressed/downloaded at the jQuery UI downloads page. They are also included in the FullCalendar download in “jquery/jquery-ui-custom.js”, all bundled and compressed into one file.
After you have gathered the dependencies, you still need to enable dragging/resizing by settings the editable option to true.