Locks the most recent undo unit of the undo stack of the application. This prevents the locked unit from being merged with undo units that are added subsequently.
Assembly: PresentationFramework (in PresentationFramework.dll)
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.