By default, the OverviewLevelLines property is -1. If the OverviewLevelLines property is -1, or indicates a non-existent level, no grid lines are shown in the chart's overview area. Use the OverviewLevelLines property to show grid lines in the chart's overview area. The OverviewVisible property shows or hides the chart's overview area. Use the Level property to access a level using its index. The LevelCount property indicates the number of levels being displayed in the control's header. Use the DrawGridLines property to specify the color of the grid lines in the overview area.