Re: no natural sign when clef changes

[Keith OHara]

Bernhard Ott <bernhard.ott <at> gmx.net> writes:
> 
> IMHO there should be a natural sign showing the f' after the 
> clef-change: am I wrong?
> 
> music = \relative c' {
>      c8 d e fis
>      c d e f
>      c8 d e fis
>      \clef "alto" c d e f
> }

This is a bug, listed at
http://code.google.com/p/lilypond/issues/detail?id=1471

The desired behavior would be to print accidentals if they either
1) differ from the previous accidental if it is "still in force" under
the chosen accidental style, OR
2) are the first after the clef change to differ from the key signature.

At the clef change, LilyPond currently resets the "still in force" list back
to the key signature.  This succeeds in repeating accidentals of case-2 such
as \clef "alto"  c d e fis , but it causes the worse problem of losing
accidentals of case-1 when these bring us back to the key signature.

I suspect the first step to a solution is simply to have LilyPond leave the 
"still in force" list un-touched at a clef changes, so that the required 
accidentals of case 1 are printed.  What I don't see, however, is a simple way
to get the courtesy accidentals printed for case 2.