I would like to be able to clear the UNDO list at will in order to try out a
series of what if situations. I am attempting to create a Suduko solver based
on 81 numbers. Each number may have a maximum of choice from nine. By
entering formulae into a greater work area where each of the possibility is
mearsured against existing entries one may reduce the choices available , in
many cases, to just one possibility.
Once these are entered one may then still be faced with multiple choices.
If the the situation requires a choice of numbers I would like the facility
to clear the UNDO list so that it retained only the entries from that point.
Should the effort result in failure one should be able to undo the entire
list, clear the list and start with the other choice of letter and so on.