How to grab and drag an element around a circle?

Question

So far I have a circle with a marker.

http://jsfiddle.net/x5APH/1/

I would like to grab and drag the marker around the circle, however the current functional

Answer 1

changed some code

        $(document).ready(function(){               

            $('#marker').on('mousedown', function(){
                $('body').on('mousemove', function(event){
                    rotateAnnotationCropper($('#innerCircle').parent(), event.pageX,event.pageY, $('#marker'));    
                });

            });                    
        }); ​

also add this code

$('body').on('mouseup', function(event){ $('body').unbind('mousemove')}); 

in the function

this is the jsfiddle http://jsfiddle.net/sandeeprajoria/x5APH/11/