bug#51821: 29.0.50; Suggest add variable or frame parameter: line-height

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: tumashu@163.com,  luangruo@yahoo.com,  51821@debbugs.gnu.org
> Date: Sun, 21 Nov 2021 09:06:44 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > No, float values are relative to the default face, which is not what
> > you want.  I meant ":height 1" or somesuch.  If that is not good
> > enough, the value of :height can be a function.
> 
> If we're going to be scaling stuff, it'd be nice if there was a setting
> that was clearly non-scaleable.  An integer value to :height would be
> possible, but pretty error-prone

How is something like ":height 1" error-prone?

> so I'd rather introduce a new keyword.

Adding a new face attribute is not a 5-min job, so if we already have
something that can work, it is better to use it.  Especially if you
want to introduce an attribute that potentially conflicts with an
existing attribute.