I am attempting to set a System.Web.UI.Control object's ID field. The control implements an interface, IChartControl, which does not have an ID property. I would like to retrieve the control as an IChartControl and set its ID field.

Should I do this?:

```
IChartControl chartControl = foo.GetChartControl();
(chartControl as Control).ID = foo.GetID();
chartControl.Bar();

```

or would it be equally right to add a new property to IChartControl named 'ID' so that when I set the ID field it sets Control's ID field.