Making \thumb behave like other fingerings

\thumb does not behave like other fingerings, in particular with regards to slur avoidance, since it is defined as a Script object. This can be changed by redefining \thumb as a Fingering object, which also allows finer control over positioning with fingeringOrientations.

\version "2.24"

%% http://lsr.di.unimi.it/LSR/Item?id=690

%LSR Slur avoidance was fixed in version 2_13_24

thumb = 
\tweak 
  text 
  \markup \fontsize #5 \musicglyph  "scripts.thumb" 
  #(make-music 'FingeringEvent)

\relative c' {
  c2\thumb
  \set fingeringOrientations = #'(right)
  <c\thumb>2
}