Why is tab unaffected by font whereas space is affected?

[Richard Wordingham]

On Mon, 20 Apr 2020 02:01:36 +0200
Kent Karlsson via Unicode <unicode at unicode.org> wrote:

> I would say that emacs stands alone with its rather strange
> interpretation. (As far as I know.)

I believe it's the standard implementation for character cell displays.
All I can say from experimentation is that the tab positions are by
default at positions defined as many character cells along.  As there
is a fair amount of code where tabs are functioning as a sequence of
spaces, it remains desirable for the default to be preserved.

I wouldn't be surprised if the Emacs behaviour were tunable - most of
Emacs is!  For example, when entering easily parsable tables of data
perforce using proportional fonts (and there doesn't seem to be a
monospace equivalent for scripts with conjuncts), it would be visually
pleasing to have a tab setting option that didn't depend on counting
character cells.

Richard.