[Solved]-Charts using Rally-Highcharts

you may see a full code example an app where a chart is updated with new data based on a selection in a release dropdown here. in that code i check if chart exists, and remove it if it does before recreating it:

if (this.down('#mychart')) {
    this.remove('mychart');
}
 this.add(
                    {
                        xtype: 'rallychart',
                        height: 400,
                        itemid: 'mychart',
                        chartconfig: {
                            //....
                        },            
                        chartdata: {
                            categories: schedulestategroups, 
                            series: [ 
                                {   
                                    //...
                                }
                            ]
                        }
                    }
                );
                this.down('#mychart')._unmask();  //otherwise loading mask does not go away