Protected Overrides Function IsModified() As Boolean
        Dim ret As Boolean = MyBase.IsModified()
        ' Enter your custom processing code here.
        Return ret

    End Function 'IsModified
End Class

' Show how to use IsModified.
' This method modifies the port property
' of the url element named Microsoft and
' saves the modification to the configuration
' file. This in turn will cause the overriden
' UrlConfigElement.IsModified() mathod to be called. 
Shared Sub ModifyElement()
    Try
        ' Get the current configuration file.
        Dim config _
        As System.Configuration.Configuration = _
        ConfigurationManager.OpenExeConfiguration( _
        ConfigurationUserLevel.None)

        ' Get the MyUrls section.
        Dim myUrlsSection As UrlsSection = _
        config.GetSection("MyUrls")


        Dim elements As UrlsCollection = _
        myUrlsSection.Urls


        Dim elemEnum As IEnumerator = _
        elements.GetEnumerator()

        Dim i As Integer = 0
        While elemEnum.MoveNext()
            If elements(i).Name = "Microsoft" Then
                elements(i).Port = 1010
                Dim [readOnly] As Boolean = _
                elements(i).IsReadOnly()
                Exit While
            End If
            i += 1
        End While

        If Not myUrlsSection.ElementInformation.IsLocked Then

            config.Save(ConfigurationSaveMode.Full)

            ' This to obsolete the MyUrls cached 
            ' section and read the updated version 
            ' from the configuration file.
            ConfigurationManager.RefreshSection("MyUrls")
        Else
            Console.WriteLine("Section was locked, could not update.")
        End If

    Catch err As ConfigurationErrorsException
        Console.WriteLine("[ModifyElement: {0}]", _
        err.ToString())
    End Try

End Sub