The latest Freecad version claims to have a robust undo-redo stack. I haven't really put it to the test yet, though. Even infinite undo does not always suffice. You may not remember exactly when and how you went off the rails, or you may have other reasons to want to look back. version control is the answer, and I just discovered that there is an add-on for exactly that: https://www.freecadweb.org/wiki/Arch_Git -- John Hasler jhasler@newsguy.com Elmwood, WI USA