Source defaults to a null reference (Nothing in Visual Basic).
OriginalSource defaults to a null reference (Nothing in Visual Basic).
Null values for Source and OriginalSource only mean that this RoutedEventArgs makes no attempt to specify the source. When this instance is used in a call to RaiseEvent, the Source and OriginalSource values are populated based on the element that raised the event and are passed on to listeners through the routing.
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.