A constant equals to 6 to represent using the mouse for drag scrolling in the reverse direction.
For normal drag scrolling with JsChartViewer.Scroll, the chart will move in the same direction as the mouse drag. However, occasionally, some designs may prefer the chart to move like dragging a scrollbar. When a scrollbar is dragged from left to right, the content will scroll from right to left. That means the chart should move in the reverse direction to the mouse drag, which is what JsChartViewer.ReverseScroll specifies.
This constant is used in JsChartViewer.setMouseUsage.