code: function (prop, name, visibility, zIndex, parent) {
  		var group = this[prop],
  			isNew = !group;
  		
  		// Generate it on first call
  		if (isNew) {	
  			this[prop] = group = this.chart.renderer.g(name)
  				.attr({
  					visibility: visibility,
  					zIndex: zIndex || 0.1 // IE8 needs this
  				})
  				.add(parent);
  		}
  		// Place it on first and subsequent (redraw) calls
  		group[isNew ? 'attr' : 'animate'](this.getPlotBox());
  		return group;		
  	}
docs: General abstraction for creating plot groups like series.group, series.dataLabelsGroup and
  series.markerGroup. On subsequent calls, the group will only be adjusted to the updated plot size.