Grapheme clusters, a.k.a.real characters

[Random832]

On Tue, Jul 18, 2017, at 22:49, Steve D'Aprano wrote:
> > What about Emoji?
> > U+1F469 WOMAN is two columns wide on its own.
> > U+1F4BB PERSONAL COMPUTER is two columns wide on its own.
> > U+200D ZERO WIDTH JOINER is zero columns wide on its own.
> 
> 
> What about them? In a monospaced font, they should follow the same rules
> I used
> above: either 0, 1 or 2 column wide.

You snipped the important part - the fact that the whole sequence of
three code points U+1F469 U+200D U+1F4BB is a single grapheme cluster
two columns wide.

You also ignored all of the other examples in my post. Did you even read
anything beyond what you snipped?