bug#20628: 25.0.50; Incorrect line height for some fonts

[Eli Zaretskii]

> Date: Sun, 24 May 2015 04:20:22 -0400
> From: Clément Pit--Claudel
>  <clement.pitclaudel@live.com>
> CC: ohwoeowho@gmail.com, 20628@debbugs.gnu.org
> 
> > How about setting the list of fonts to be ignored (assuming Emacs
> > acquires such a capability) -- would that be useful for packages?
> 
> Maybe. The problem is that if a good font is not installed yet, ignoring 
> Latin Modern Math means replacing huge lines with square boxes. I'm not sure 
> which one is best. Ignoring Latin Modern Math may be better because fixing 
> the square boxes then only requires installing a new font (while fixing the 
> line heights requires installing a new font /and/ setting up fontsets in 
> Emacs). But ignoring Latin Modern Math is also more confusing (the symbols 
> will display fine in user's web browsers, but not in Emacs). The unearthing 
> of `face-ignored-fonts' likely makes this an easy change; do you have an 
> opinion either way?

I think it is better top ignore fonts that produce display which is
unacceptable to users.  You can include in the installation
instructions advice on which fonts to install.