function dispatchDownplayAction(seriesModel, dataName, api) {
	        // If element hover will move to a hoverLayer.
	        var el = api.getZr().storage.getDisplayList()[0];
	        if (!(el && el.useHoverLayer)) {
	            seriesModel.get('legendHoverLink') && api.dispatchAction({
	                type: 'downplay',
	                seriesName: seriesModel.name,
	                name: dataName
	            });
	        }
	    }
Layout list like component.
It will box layout each items in group of component and then position the whole group in the viewport
@param {module:zrender/group/Group} group
@param {module:echarts/model/Component} componentModel
@param {module:echarts/ExtensionAPI}