Occurs when the value of the System.Web.UI.WebControls.HiddenField control changes between posts to the server.
The HiddenField.ValueChanged event is raised when the value of the System.Web.UI.WebControls.HiddenField control changes between posts to the server. This allows you to provide an event-handling method that performs a custom routine whenever this event occurs.
For more information about handling events, see Consuming Events.