I observed a number of things, but I'm not sure whether they're built-in features / restrictions or whether they're bugs:
1. when using only 'left' or 'right' position specifier, notes in unison or a second apart will have overlapping fingerings (measures 2, 3 & 9)
2. you cannot specify 'left' and 'right' at the same time to mean "left or right" (measure 9)
3. providing an empty position specifier list does not work as described in the documentation (it should hide the fingerings - which it doesn't) (measure
4. two notes in unison can have fingerings added to the wrong notehead (measures 7 & 8)
5. why are fingerings of unison notes never displayed at the same height (vertical position)?
Here's a short yet rather exhaustive example snippet displaying the actual output for 10 different combinations of fingering placement specs:
%%%% BEGIN snippet
\version "2.16.2"
theChord = { <e-1 cis'-3 g'-2 a-0>4 <e-1 e-3 g'-2 a-0> }
theMusic = \new Staff {
\relative c, {
\key c \major
\time 2/4
\clef "bass"
\override Score.RehearsalMark #'self-alignment-X = #LEFT
\override Score.BarNumber #'break-visibility = #'#(#f #t #t)
\set Score.barNumberVisibility = #(every-nth-bar-number-visible 1)
\override Score.BarNumber #'stencil
= #(make-stencil-boxer 0.1 0.25 ly:text-interface::print)
\bar ""
\mark \markup{ \rounded-box { "default" } } |
\theChord
\mark \markup{ \rounded-box { "right" } } |
\set fingeringOrientations = #'(right)
\theChord
\mark \markup{ \rounded-box { "left" } } |
\set fingeringOrientations = #'(left)
\theChord
\mark \markup{ \rounded-box { "up" } } |
\set fingeringOrientations = #'(up)
\theChord
\mark \markup{ \rounded-box { "down" } } |
\set fingeringOrientations = #'(down)
\theChord
\mark \markup{ \rounded-box { "empty (spawns warning)" } } |
\set fingeringOrientations = #'()
\theChord
\mark \markup{ \rounded-box { "up left down" } } |
\set fingeringOrientations = #'(up left down)
\theChord
\mark \markup{ \rounded-box { "up right down" } } |
\set fingeringOrientations = #'(up right down)
\theChord
\mark \markup{ \rounded-box { "left right" } } |
\set fingeringOrientations = #'(left right)
\theChord
\mark \markup{ \rounded-box { "up down" } } |
\set fingeringOrientations = #'(up down)
\theChord
\bar "|."
}
}
\score {
\theMusic
\layout {}
}
%%%% END snippet