Note: This method is new in the .NET Framework version 2.0.
Invalidates the whole area of the control that is displayed on the design surface and signals the control designer to redraw the control.
Namespace: System.Web.UI.Design Assembly: System.Design (in system.design.dll)
The Invalidate method provides the design host with a way to instruct the control designer to redraw the control. Essentially, this is the same as calling UpdateDesignTimeHtml method, because it causes the whole control to be redrawn.