title: How to push an operation onto the Excel undo stack?
body: <p>I'm building a VSTO Excel add-in that manipulates the values of multiple cells.  I would like to allow the user to undo and redo the changes created by the add-in via the standard Excel features.  I prefer to avoid using VBA.</p>
  
  <p>Is this possible?  If so, how?</p>
  
  <p>Another question: is it possible to examine the existing undo/redo stack?</p>