Drill down allows you to get a more detailed view of the data, or somehow clarify chart element. The Manco.Chart control has special “DrillDown” event for this purposes. This event occurs when user double clicks chart element. Currently it’s supported for 2D charts only. In the drill down event handler you can load another data to the chart document and redraw chart to get a more detailed view, or show some kind of the message box, or something else.