Some time ago, Peter Blois posted "Snoop", a tool which I find really useful for debugging WPF applications. It allows you to:

  • Browse the visual tree of running WPF applications
  • Inspect properties of elements at runtime
  • Edit properties of elements at runtime
  • Inspect RoutedEvents that are occurring, including the elements that handle them
  • Magnify sections of the UI
  • Find and debug binding errors
  • Snoop screenshot

    You may find more info and downloads on the Snoop official web page:

    http://www.blois.us/Snoop/