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.
Call this method when a non-text undo unit is added to the application's main undo stack. This prevents the locked unit from being merged with undo units that are added subsequently.
Supported in: 4.6, 4.5, 4, 3.5, 3.0
.NET Framework Client Profile
Supported in: 4, 3.5 SP1
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.