Do you think you've discovered an error in this book? Please check the list of errata below to see if we've already addressed the error. If not, please submit the error via our Errata Form. We will attempt to verify your error; if you're right, we will post a correction below.

Error   1          The type or namespace name 'DispatcherTimer' could not be found (are you missing a using directive or an assembly reference?)        

using System.Windows.Threading;