The ActiveRegion property corresponds to the bounds of a RadChart's item. It is useful to show tooltips and it also contains an additional string property named Url. ActiveRegion appears for many of the UI elements in the chart including labels, chart series, chart series items, chart title, legend, axis items and the empty series message.
The ActiveRegion property has two significant for WinForms properties:
ToolTip: A text description of an item's area that is displayed when the mouse hovers over it.
Url: A string property which can be used for an additional information or in a scenario where you would want to open an external website
To set a ToolTip, select an item that you are interested in. Then navigate to its ActiveRegion property. In the ToolTip enter descriptive text.
Below is the ActiveRegion for a chart series item. If the mouse hovers over that area in the chart the tool tip "Sales - January" will display.