This method is called during a postback if this control has been visible when being rendered to the client.
Private Sub System#Web#UI#IPostBackDataHandler#LoadPostData( _
true if the server control's state changes as a result of the post back; otherwise false.
If the controls has been visible when being rendering to the client, RegisterRequiresPostBack has been called during OnPreRender
UserControl Class | Spring.Web.UI Namespace