bug#36156: [PATCH] Make toolbar show keyboard equivalents in its tooltips

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Sun, 25 Aug 2019 14:58:42 +0200
> Cc: Juri Linkov <juri@linkov.net>, 36156@debbugs.gnu.org
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Are we sure TOOL_BAR_ITEM_CAPTION will always produce human-readable
> > text?
> 
> I think so, because we do this above (quoted to avoid gmail mangling the 
> code):
> 
> >  /* Get the caption of the item.  If the caption is not a string,
> >     evaluate it to get a string.  If we don't get a string, skip this
> >     item.  */
> >  caption = XCAR (item);
> >  if (!STRINGP (caption))
> >    {
> >      caption = menu_item_eval_property (caption);
> >      if (!STRINGP (caption))
> >    return 0;
> >    }
> >  set_prop (TOOL_BAR_ITEM_CAPTION, caption);
> 
> When this function returns 0, we don't append this item to the items
> that will be displayed.

That just makes sure it's a string, but what kind of string is that?
A caption can be something unpalatable, like "OpNuFil".