metric for block coverage

[Eli Zaretskii via Unicode]

> Cc: unicode-request at unicode.org
> Date: Sun, 18 Feb 2018 14:35:00 +0100
> From: "Janusz S. Bień via Unicode" <unicode at unicode.org>
> 
> As a Debian user using some rare characters for old Polish
> transliteration I would be happy with a tool which scans
> available/installed fonts for a specific list of characters and shows
> only those fonts which support the whole list. Of course showing also
> the characters in question would be very desirable.

I'm sure you know about BabelMap.  It has such a feature.