1) addDragMoveHandler--- it will work, While moving the jobs from origin to destinaton origin.
2) addDragStartHandler-- When starting of drag will work., In this we can cancel the event using args.set_cancel(true);
3) addDragEndHandler--- it will work, After drop handler event fired,
4) addDragLeaveHandler--- it will work,after move out from the source block,
5) addDragCancelHandler--- it will work, After dragging not dropping to destination.
6) _removeHandler --It will remove only specified event handler.
7) clearHandler--It will clear all the event handler.
