Undo framework in C#

There are two pages for a good undo framework.

http://blogs.msdn.com/kirillosenkov/archive/2009/07/02/samples-for-the-undo-framework.aspx

http://blogs.msdn.com/kirillosenkov/archive/2009/06/29/new-codeplex-project-a-simple-undo-redo-framework.aspx