[AccessD] Continuous form question

Hello:

I have a large continuous form which will normally be showing about 600 rows
of around 20 columns.  After editing it, my client would like some kind of
visual clue as to which individual cells in the form have been updated, so
that someone else can quickly look it over and see where changes have been
made. Does anyone have a good way of doing this?  So far, any way I've
thought about has been really ugly to implement.

Thanks,

Doug Steele