code: function dragStart(_dragElement, ev, ui) {
  		hoverListener.start(function(cell) {
  			clearOverlays();
  			if (cell) {
  				if (getIsCellAllDay(cell)) {
  					renderCellOverlay(cell.row, cell.col, cell.row, cell.col);
  				}else{
  					var d1 = realCellToDate(cell);
  					var d2 = addMinutes(cloneDate(d1), opt('defaultEventMinutes'));
  					renderSlotOverlay(d1, d2);
  				}
  			}
  		}, ev);
  	}
docs: /* External Dragging
  --------------------------------------------------------------------------------