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Gets the IChartArea object that represents the complete chart area of the chart.
The chart area contains the chart elements outside the plotted data region, such as the chart title and legend. The plot area is the region where the chart's data is drawn; see PlotArea.
IChartArea ChartArea { get; }
ReadOnly Property ChartArea As IChartArea
IChart chart = worksheet.Shapes.AddChart(ChartType.ColumnClustered, 20, 20, 300, 200).Chart;
IChartArea chartArea = chart.ChartArea;
chartArea.Format.Fill.Color.RGB = Color.Red;