What is the correct way to set TAdvMemo.Modified (RO property) property to "false"?

I know that TAdvMemo.ClearModified and  TAdvMemo.ClearUndoRedo  can set it to "false" but I don't want to loose Undo history.

Does exist the another way to put memo to unmodified state?



AdvMemo.Modified := false

resets the modified state. This indeed will clear the Undo buffer and this is by design. Only when the grid is in modified state does it make sense that an undo is possible.

Thanks for answer. I'm confused... For some reason I was sure that is property is read-only...
But I'm not sure regarding resetting undo history. It's absolutely naturally if user wants to rollback his job to a few steps ago, independently when he save this job.
And the most popular IDE implement the such behaviour (Delphi, Visual Studio, Notepad++, PSPad…). 
Is it possible for TadvMemo to keep undo history when doc is saving? Maybe TUndoList object can help me? Please give me any advices.