https://bugzilla.redhat.com/show_bug.cgi?id=1437999
--- Comment #56 from Alexei Podtelezhnikov apodtele@gmail.com --- (In reply to Bojan Smojver from comment #55)
If you compare 8 old with 8.25 new for Liberation Mono (which are supposed to be the same, according to the discussion above), you'll notice that they are not quite the same.
I aligned old "8" and new "8.25" side by side. They have identical line spacing. Ftdiff relies on face->size->metrics.height that is properly scaled.