Registers a control as one that requires postback handling when the page is posted back to the server.
The control to be registered must implement the System.Web.UI.IPostBackDataHandler interface or an System.Web.HttpException is raised. When implemented by a control, the System.Web.UI.IPostBackDataHandler interface enables handling of post back data and raising of any post back data changed events. For more information on the server control event model, see ASP.NET Server Control Event Model.
Register controls with the page at or before the Page_PreRender event of the page life cycle.