Faking ff ligatures

[Rebecca and Rowland]

I've just installed some founts with the help of fontinst, and I've noticed
that while the method for faking `ff' ligatures seems to work very well in
some cases, it doesn't work at all well in others.  In these cases, the
`ff' ligature looks like just two separate fs, and when you have a
combination like `ffl' and `ffi' with the `fl' and `fi' ligatures in place,
the result is rather horrible.

So...  Does anyone know what might be done about this?  I was thinking in
terms of adding a tweak to the ligature faking code to bring the two fs
closer together.

It seems to me that the code needing modifying is in latin.mtx:

\setglyph{ff}
   \glyph{f}{1000}
   \movert{\kerning{f}{f}}
   \glyph{f}{1000}
\endsetglyph

And that I need to (for each fount concerned) work out a suitable value to
reduce the space by.  Something like (in latin.mtx saved as latin-foo.mtx
or similar):

\movert{\neg{\scale{\width{f}}{250}}}

Is this not entirely insane?

Rowland.