Assembly: Microsoft.ReportViewer.WebForms (in microsoft.reportviewer.webforms.dll)
By default, theThe ReportViewer control shows the wait control only when it determines that a postback is caused by the ReportViewer control itself. Registering your custom control using this method allows you to cause the wait control to be displayed as a result of an action on the custom control. This method registers the specified control and all the child controls that it contains.
To enable and disable your custom control, you should subscribe to a property change event for the Microsoft.Reporting.WebFormsClient.isLoading client-side property to be notified when the ReportViewer postback starts and ends. For more information on how to use the client-side control, see Microsoft.Reporting.WebFormsClient.ReportViewer Class.