An IOleUndoManager client can expose this interface to be informed when the undo stack has returned to an unmodified state (that is, no data-changing modifications exist) by the undo manager.
Assembly: Microsoft.VisualStudio.TextManager.Interop (in Microsoft.VisualStudio.TextManager.Interop.dll)
Informs the client that the document has returned to a clean state.
This interface is used to remove the asterisk that indicates that a document is not in the clean state.
Notes to Implementers:
Implement this interface to have the undo manager inform you of when the undo stack returns to an unmodified state.