' Implement the SaveViewState method. If the StateBag
' that stores the MyItem class's view state contains
' a value for the message property and if the value
' has changed since the TrackViewState method was last 
' called, all view state for this class is deleted, 
' using the StateBag.Clear method,and the new value is added.
Function SaveViewState() As Object Implements IStateManager.SaveViewState
    ' Check whether the message property exists in 
    ' the ViewState property, and if it does, check
    ' whether it has changed since the most recent
    ' TrackViewState method call.
    If Not CType(_viewstate, IDictionary).Contains("message") OrElse _viewstate.IsItemDirty("message") Then
        _viewstate.Clear()
        ' Add the _message property to the StateBag.
        _viewstate.Add("message", _message)
    End If
    Return CType(_viewstate, IStateManager).SaveViewState()
End Function 'IStateManager.SaveViewState