Andy Wiggins wrote...
Blinking is not part of the Excel interface, which was the area I
understood
the OP to be asking about.

I accept that your code produces the blinking effect, but at what
expense?
It's based on a never-ending Do loop. This code goes into my museum of
time-wasters.
....

Most of the udfs posted in the Excel newsgroups address formula
calculation functionality that isn't built in. Should we refrain from
providing such udfs and just tell the OPs it can't be done?

You screwed up and failed to state clearly that there was no built-in
functionality to do so. I agree that the VBA needed to accomplish it
isn't worth the performance drag (though I don't share your unthinking
bias against unending loops - whatcha think is the core of Windows's
System Idle Process?), but the plain fact is that what the OP asked
about *CAN* be done. Whether it's worth doing so is up to the OP, not
you or me.