bug#33232: `gnus-summary-line-format' padding doesn’t work in gui when there are multiple-column-width characters

[Eli Zaretskii]

> From: Eric Abrahamsen <eric@ericabrahamsen.net>
> Date: Thu, 01 Nov 2018 15:52:14 -0700
> 
> Someone just reported something similar on the org list, that
> `string-width' doesn't return the actual width occupied by the string,
> which you'd think would be the whole point.

string-width does the best job it can, but you cannot hope to get
exact results when using variable-width fonts.  What string-width
returns should be correct on TTY frames, and only an approximation of
GUI frames, when you mix scripts and thus fonts in the same string.

For pixel-level accuracy on display, you must use display 'space' and
'align' properties.