New tablature features

this patch includes:
1) tablature is now "numbers only" as default
2) dead notes and palm mute is supported
3) "tied to" fret numbers become invisible
   (or parenthesized after line breaks or in a second volta)
4) the slope of glissando lines points in the right direction
5) grace notes (even parenthesized) are represented by smaller
   fret numbers.

15 files changed, 556 insertions, 18 deletions

diff --git a/input/regression/dead-notes.ly b/input/regression/dead-notes.ly
new file mode 100644
index 0000000000..253fdd5bf3
--- /dev/null
+++ b/input/regression/dead-notes.ly
@@ -0,0 +1,26 @@
+\version "2.13.4"
+
+\header{ texidoc = "Muted notes (also called dead notes) are supported
+                    within normal staves and tablature."
+       }
+
+deadnotes = \relative c,, {
+   e8. \deadNotesOn e16 \deadNotesOff g4 a b |
+   e8. \deadNote e16 g4 a b |
+   e,4. \deadNote { e8 e e } e4 |
+   < e, \deadNote b' e >8 < e \deadNote b' e > < e \deadNote b' e >4 < e \deadNote b' e >4 r
+   \bar "|."
+}
+
+\context StaffGroup <<
+  \context Staff <<
+    \clef "bass_8"
+    \deadnotes
+  >>
+  \context TabStaff <<
+    \set TabStaff.stringTunings = #bass-tuning
+    \deadnotes
+  >>
+>>
+
+
diff --git a/input/regression/modern-tab-clef-scaled.ly b/input/regression/modern-tab-clef-scaled.ly
new file mode 100644
index 0000000000..12caf11139
--- /dev/null
+++ b/input/regression/modern-tab-clef-scaled.ly
@@ -0,0 +1,39 @@
+\version "2.13.4"
+
+\header{ texidoc = "The sans serif style tab clef is automatically adjusted to
+                    different string spacings."
+       }
+
+guitar = \relative c {
+  c4 d e f
+  e4 d c2
+}
+
+\score {
+  <<
+    \new Staff {
+      \clef "treble_8"
+      \guitar
+    }
+    \new TabStaff {
+      \clef "moderntab"
+      \set TabStaff.stringTunings = #guitar-tuning
+      \guitar
+    }
+  >>
+}
+
+\score {
+  <<
+    \new Staff {
+      \clef "treble_8"
+      \guitar
+    }
+    \new TabStaff {
+      \clef "moderntab"
+      \set TabStaff.stringTunings = #guitar-tuning
+      \override TabStaff.StaffSymbol #'staff-space = #1.0 % default value is 1.5
+      \guitar
+    }
+  >>
+}
\ No newline at end of file
diff --git a/input/regression/modern-tab-clef.ly b/input/regression/modern-tab-clef.ly
new file mode 100644
index 0000000000..d95fb23bcb
--- /dev/null
+++ b/input/regression/modern-tab-clef.ly
@@ -0,0 +1,44 @@
+\version "2.13.4"
+
+\header{ texidoc = "Sans serif style tab clefs are supported by @code{\\clef moderntab}.
+                    This alternative clef supports four- to seven-stringed instruments
+                    and is scaled automatically."
+       }
+
+bass = \relative c, {
+  c4 d e f
+  e4 d c2
+}
+
+guitar = \relative c {
+  c4 d e f
+  e4 d c2
+}
+
+\score {
+  <<
+    \new Staff {
+      \clef "bass_8"
+      \bass
+    }
+    \new TabStaff {
+      \clef "moderntab"
+      \set TabStaff.stringTunings = #bass-four-string-tuning
+      \bass
+    }
+  >>
+}
+
+\score {
+  <<
+    \new Staff {
+      \clef "treble_8"
+      \guitar
+    }
+    \new TabStaff {
+      \clef "moderntab"
+      \set TabStaff.stringTunings = #guitar-seven-string-tuning
+      \guitar
+    }
+  >>
+}
\ No newline at end of file
diff --git a/input/regression/palm-mute.ly b/input/regression/palm-mute.ly
new file mode 100644
index 0000000000..33123f3f8e
--- /dev/null
+++ b/input/regression/palm-mute.ly
@@ -0,0 +1,27 @@
+\version "2.13.4"
+
+\header{ texidoc = "The palm mute technique for stringed instruments
+                    is supported by triangle-shaped note heads."
+       }
+
+palmmute = \relative c, {
+    \time 4/4
+    e8^\markup { \musicglyph #"noteheads.u2do"  = palm mute }
+    \palmMuteOn e e \palmMuteOff  e e  \palmMute e e e |
+    e8 \palmMute { e e e } e e e e |
+    \palmMuteOn < e b' e >8 e e e < e b' e >2 \palmMuteOff |
+    < \palmMute e b' e >8 \palmMute { e e e } < \palmMute e b' e >2
+    \bar "|."
+}
+
+\context StaffGroup <<
+  \context Staff <<
+    \clef "G_8"
+    \palmmute
+  >>
+  \context TabStaff <<
+    \palmmute
+  >>
+>>
+
+
diff --git a/input/regression/tablature-full-notation.ly b/input/regression/tablature-full-notation.ly
new file mode 100644
index 0000000000..80a48688be
--- /dev/null
+++ b/input/regression/tablature-full-notation.ly
@@ -0,0 +1,36 @@
+\version "2.13.4"
+
+\header{ texidoc = "As default, tablature staves show only the fret numbers, because
+                    in most situations, they are combined with normal staves.
+                    When used without standard notation, @code{tabFullNotation}
+                    can be used."
+       }
+
+tabstuff = {
+  \time 3/4
+  c4^"test" d( e)
+  f4\f g a^\fermata
+  c8\<\( c16 c ~ c2\!
+  c'2.\)
+  \mark \default
+  R2.
+  r4 d4 r8 e
+  \times 3/4 { b4 c \glissando d\5 \glissando c }
+  c4. d-_( e\varcoda)
+  ->f g~ a\prall g\thumb e-.
+  \bar "|."
+}
+
+\score {
+  <<
+    \new Staff { \clef "G_8" \tabstuff }
+    \new TabStaff   { \tabstuff }
+  >>
+}
+
+\score {
+  \new TabStaff {
+    \tabFullNotation
+    \tabstuff
+  }
+}
diff --git a/input/regression/tablature-glissando.ly b/input/regression/tablature-glissando.ly
new file mode 100644
index 0000000000..17db67a307
--- /dev/null
+++ b/input/regression/tablature-glissando.ly
@@ -0,0 +1,23 @@
+\version "2.13.4"
+
+\header{ texidoc = "Glissando lines in tablature have the right slope."
+       }
+
+\paper { ragged-right = ##f } % strech the staff to make glissando lines visible
+
+glissandotest = \relative c {
+   c4\5 \glissando d\5 \glissando e\5 f\5 |
+   c4\5 \glissando d\5 \glissando c2\5 |
+   c4\5 \glissando c'\4 c\4 \glissando c,\5
+  \bar "|."
+}
+
+\context StaffGroup <<
+  \context Staff <<
+    \clef "G_8"
+    \glissandotest
+  >>
+  \context TabStaff <<
+    \glissandotest
+  >>
+>>
diff --git a/input/regression/tablature-grace-notes.ly b/input/regression/tablature-grace-notes.ly
new file mode 100644
index 0000000000..5012ddd643
--- /dev/null
+++ b/input/regression/tablature-grace-notes.ly
@@ -0,0 +1,24 @@
+\version "2.13.4"
+
+\header{ texidoc = "Fret numbers belonging to grace notes are smaller."
+       }
+
+gracenotes = \relative c {
+   c4 d e f
+   \grace e8 c4 d e f
+   \grace \parenthesize e8 c4 d e f
+   \appoggiatura e8 c4 d e f
+   \acciaccatura e8 c4 d e f
+   \bar "|."
+}
+
+\context StaffGroup <<
+  \context Staff <<
+    \clef "G_8"
+    \gracenotes
+  >>
+  \context TabStaff <<
+    \gracenotes
+  >>
+>>
+
diff --git a/input/regression/tablature-tie-behaviour.ly b/input/regression/tablature-tie-behaviour.ly
new file mode 100644
index 0000000000..8760c9f204
--- /dev/null
+++ b/input/regression/tablature-tie-behaviour.ly
@@ -0,0 +1,31 @@
+\version "2.13.4"
+
+\header{ texidoc = "In tablature, notes that are tied to are invisible
+                    except after a line break or within a second volta;
+                    here, the fret number is displayed in parentheses."
+       }
+
+tietest = \relative c {
+  \override Voice.StringNumber #'transparent = ##t % remove circled string numbers
+  \repeat volta 2 {
+    f2 ~ f4  e
+    g8 g ~ g g ~ g g~ g g ~
+    g1
+    c1 ~ \break  c2 ~ c
+    < c\3 e\2 g\1 >4 < c\3 e\2 g\1 > ~ < c\3 e\2 g\1 >\laissezVibrer r
+    c4. d8 e2 ~
+  }
+  \alternative { { e2 r } { e2\repeatTie e2^\fermata } }
+  \bar "|."
+}
+
+\context StaffGroup <<
+  \context Staff <<
+    \clef "G_8"
+    \tietest
+  >>
+  \context TabStaff <<
+    \tietest
+  >>
+>>
+
diff --git a/ly/engraver-init.ly b/ly/engraver-init.ly
index 9d19e92cdb..348d1a8c47 100644
--- a/ly/engraver-init.ly
+++ b/ly/engraver-init.ly
@@ -628,6 +628,7 @@ automatically when an output definition (a @code{\score} or
     (Voice Stem direction ,UP)
     (Voice Stem font-size -3)
     (Voice NoteHead font-size -3)
+    (Voice TabNoteHead font-size -4)
     (Voice Dots font-size -3)
     (Voice Stem length-fraction 0.8)
     (Voice Stem no-stem-extend #t)
@@ -716,12 +717,39 @@ context."
 
   %% No accidental in tablature !
   \remove "Accidental_engraver"
-
-  \override Glissando #'extra-dy = #0.75
+  %% remove stems, beams, dots and rests ...
+  \override Stem #'stencil = ##f
+  \override Beam #'stencil = ##f
+  \override Dots #'stencil = ##f
+  \override Rest #'stencil = ##f
+  \override MultiMeasureRest #'stencil = ##f
+  %% ... all kinds of ties/slurs
+  \override Tie  #'stencil = ##f
+  \override RepeatTie #'stencil = ##f
+  \override LaissezVibrerTie #'stencil = ##f
+  \override Slur #'stencil = ##f
+  \override PhrasingSlur #'stencil = ##f
+  %% 'tied to' fret numbers become invisible or parenthesized, respectively)
+  \override Tie #'after-line-breaking = #tie::handle-tab-tie
+  \override RepeatTie #'after-line-breaking = #repeat-tie::parenthesize-tab-note-head
+  %% ... and all kinds of markups, spanners etc.
+  \override TupletBracket #'stencil = ##f
+  \override TupletNumber #'stencil = ##f
+  \override DynamicText #'transparent = ##t
+  \override DynamicTextSpanner #'stencil = ##f
+  \override TextSpanner #'stencil = ##f
+  \override Hairpin #'transparent = ##t
+  \override Script #'stencil = ##f
+  \override TextScript #'stencil = ##f
+  %% the direction for glissando lines will be automatically corrected
+  \override Glissando #'extra-dy = #glissando::calc-tab-extra-dy
   \override Glissando #'bound-details #'right = #`((attach-dir . ,LEFT)
 						   (padding . 0.3))
   \override Glissando #'bound-details #'left = #`((attach-dir . ,RIGHT)
 						   (padding . 0.3))
+  %% dead notes
+  \override TabNoteHead #'glyph-name = #tab-note-head::calc-glyph-name
+  \override TabNoteHead #'stencil = #tab-note-head::whiteout-if-style-set
 }
 
 \context {
@@ -746,6 +774,14 @@ context."
   \remove "Accidental_engraver"
   \remove "Key_engraver"
   \remove "String_number_engraver"
+  %% the clef handler
+  \override Clef #'stencil = #clef::print-modern-tab-if-set
+  %% no time signature
+  \override TimeSignature #'stencil = ##f
+  %% better parentheses in a TabStaff
+  \override ParenthesesItem #'stencils = #parentheses-item::calc-tabstaff-parenthesis-stencils
+  %% no arpeggios
+  \override Arpeggio #'stencil = ##f
   %% Special "TAB" clef
   clefGlyph = #"clefs.tab"
   clefPosition = #0
diff --git a/ly/property-init.ly b/ly/property-init.ly
index fd5c766ef7..f91c4b8d85 100644
--- a/ly/property-init.ly
+++ b/ly/property-init.ly
@@ -420,3 +420,84 @@ pointAndClickOff = #(define-music-function (parser location) ()
 pointAndClickOn = #(define-music-function (parser location) ()
                       (ly:set-option 'point-and-click #t)
                       (make-music 'SequentialMusic 'void #t))
+
+palmMuteOn = {
+  \override NoteHead #'style = #'do
+}
+
+palmMuteOff = {
+  \revert NoteHead #'style
+}
+
+palmMute =
+#(define-music-function (parser location note) (ly:music?)
+  ;; are we inside a <...>?
+  (if (eq? (ly:music-property note 'name) 'NoteEvent)
+      ;; yes -> add a tweak
+      (begin (set! (ly:music-property note 'tweaks)
+                    (acons 'style 'do (ly:music-property note 'tweaks)))
+      note)
+      ;; no -> use predefined commands to switch to triangle-shaped note heads
+      #{
+        \palmMuteOn
+        $note
+        \palmMuteOff
+      #}))
+
+deadNotesOn = {
+  \override TabNoteHead #'style = #'cross
+  \override NoteHead #'style = #'cross
+}
+
+deadNotesOff = {
+  \revert TabNoteHead #'style
+  \revert NoteHead #'style
+}
+
+deadNote =
+#(define-music-function (parser location note) (ly:music?)
+  ;; are we inside a <...>?
+  (if (eq? (ly:music-property note 'name) 'NoteEvent)
+      ;; yes -> add a tweak
+      (begin (set! (ly:music-property note 'tweaks)
+                    (acons 'style 'cross (ly:music-property note 'tweaks)))
+       note)
+       ;; no -> use predefined commmands for changing
+       ;; note head and tablature fret signs
+       #{
+         \deadNotesOn
+         $note
+         \deadNotesOff
+       #}))
+
+tabFullNotation = {
+  % time signature
+  \revert TabStaff.TimeSignature #'stencil
+  % stems (the half note gets a double stem)
+  \override TabVoice.Stem #'stencil = #tabvoice::draw-double-stem-for-half-notes
+  % beams, dots
+  \revert TabVoice.Beam #'stencil
+  \revert TabVoice.Dots #'stencil
+  \revert TabVoice.Tie #'stencil
+  \revert TabVoice.Tie #'after-line-breaking
+  \revert TabVoice.RepeatTie #'stencil
+  \revert TabVoice.RepeatTie #'after-line-braking
+  \revert TabVoice.LaissezVibrerTie #'stencil
+  \revert TabVoice.Slur #'stencil
+  \revert PhrasingSlur #'stencil
+  % tuplet stuff
+  \revert TabVoice.TupletBracket #'stencil
+  \revert TabVoice.TupletNumber #'stencil
+  % dynamic signs
+  \revert DynamicText #'transparent
+  \revert DynamicTextSpanner #'stencil
+  \revert TabVoice.DynamicTextSpanner #'stencil
+  \revert TabVoice.Hairpin #'transparent
+  % rests
+  \revert TabVoice.Rest #'stencil
+  \revert TabVoice.MultiMeasureRest #'stencil
+  % markups etc.
+  \revert TabVoice.Script #'stencil
+  \revert TabVoice.TextScript #'stencil
+  \revert TabStaff.Arpeggio #'stencil
+}
diff --git a/scm/lily.scm b/scm/lily.scm
index 7aa8c05c20..783679ca04 100644
--- a/scm/lily.scm
+++ b/scm/lily.scm
@@ -397,6 +397,7 @@ LilyPond safe mode.  The syntax is the same as `define*-public'."
     "paper.scm"
     "backend-library.scm"
     "x11-color.scm"
+    "tablature.scm"
 
     ;; must be after everything has been defined
     "safe-lily.scm"))
diff --git a/scm/music-functions.scm b/scm/music-functions.scm
index c5e6f2da01..1372a15a52 100644
--- a/scm/music-functions.scm
+++ b/scm/music-functions.scm
@@ -384,6 +384,7 @@ i.e.  this is not an override"
 			;; TODO: take this from voicedGraceSettings or similar.
 			'((Voice Stem font-size -3)
 			  (Voice NoteHead font-size -3)
+                          (Voice TabNoteHead font-size -4)
 			  (Voice Dots font-size -3)
 			  (Voice Stem length-fraction 0.8)
 			  (Voice Stem no-stem-extend #t)
diff --git a/scm/output-lib.scm b/scm/output-lib.scm
index f9b920f37d..db1181f740 100644
--- a/scm/output-lib.scm
+++ b/scm/output-lib.scm
@@ -89,22 +89,6 @@
   ))
 
 
-; default tunings for common string instruments
-(define-public guitar-tuning '(4 -1 -5 -10 -15 -20))
-(define-public guitar-open-g-tuning '(2 -1 -5 -10 -17 -22))
-(define-public bass-tuning '(-17 -22 -27 -32))
-(define-public mandolin-tuning '(16 9 2 -5))
-
-;; tunings for 5-string banjo
-(define-public banjo-open-g-tuning '(2 -1 -5 -10 7))
-(define-public banjo-c-tuning '(2 -1 -5 -12 7))
-(define-public banjo-modal-tuning '(2 0 -5 -10 7))
-(define-public banjo-open-d-tuning '(2 -3 -6 -10 9))
-(define-public banjo-open-dm-tuning '(2 -3 -6 -10 9))
-;; convert 5-string banjo tuning to 4-string by removing the 5th string
-(define-public (four-string-banjo tuning)
-  (reverse (cdr (reverse tuning))))
-
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; note heads
 
diff --git a/scm/parser-clef.scm b/scm/parser-clef.scm
index fff8f1b83d..a6d178eaef 100644
--- a/scm/parser-clef.scm
+++ b/scm/parser-clef.scm
@@ -132,3 +132,10 @@
 		       (sort (map car supported-clefs) string<?)))
 	  (make-music 'Music)))))
 
+;; a function to add new clefs at runtime
+(define-public (add-new-clef clef-name clef-glyph clef-position octavation c0-position)
+  "Append the entries for a clef symbol to supported clefs and c0-pitch-alist"
+  (set! supported-clefs
+        (acons clef-name (list clef-glyph clef-position octavation) supported-clefs))
+  (set! c0-pitch-alist
+        (acons clef-glyph c0-position c0-pitch-alist)))
diff --git a/scm/tablature.scm b/scm/tablature.scm
new file mode 100644
index 0000000000..3d92e76d65
--- /dev/null
+++ b/scm/tablature.scm
@@ -0,0 +1,178 @@
+;;;; tablature.scm
+;;;;
+;;;; source file of the GNU LilyPond music typesetter
+;;;;
+;;;; (c) 2009 Marc Hohl <marc@hohlart.de>
+
+;; default tunings for common string instruments
+;; guitar tunings
+(define-public guitar-tuning '(4 -1 -5 -10 -15 -20))
+(define-public guitar-seven-string-tuning '(4 -1 -5 -10 -15 -20 -25))
+(define-public guitar-drop-d-tuning '(4 -1 -5 -10 -15 -22))
+(define-public guitar-open-g-tuning '(2 -1 -5 -10 -17 -22))
+;; bass tunings
+(define-public bass-tuning '(-17 -22 -27 -32))
+(define-public bass-four-string-tuning '(-17 -22 -27 -32))
+(define-public bass-drop-d-tuning '(-17 -22 -27 -34))
+(define-public bass-five-string-tuning '(-17 -22 -27 -32 -37))
+(define-public bass-six-string-tuning '(-12 -17 -22 -27 -32 -37))
+;; mandolin
+(define-public mandolin-tuning '(16 9 2 -5))
+;; tunings for 5-string banjo
+(define-public banjo-open-g-tuning '(2 -1 -5 -10 7))
+(define-public banjo-c-tuning '(2 -1 -5 -12 7))
+(define-public banjo-modal-tuning '(2 0 -5 -10 7))
+(define-public banjo-open-d-tuning '(2 -3 -6 -10 9))
+(define-public banjo-open-dm-tuning '(2 -3 -6 -10 9))
+;; convert 5-string banjo tuning to 4-string by removing the 5th string
+(define-public (four-string-banjo tuning)
+  (reverse (cdr (reverse tuning))))
+
+;; for more control over glyph-name calculations,
+;; we use a custom callback for tab noteheads
+;; which will ignore 'style = 'do
+(define-public (tab-note-head::calc-glyph-name grob)
+  (let ((style (ly:grob-property grob 'style)))
+   (case style
+      ((cross) "2cross"))))
+
+;; ensure we only call notehead callback when
+;; 'style = 'cross
+(define-public (tab-note-head::whiteout-if-style-set grob)
+  (let ((style (ly:grob-property grob 'style)))
+       (if (and (symbol? style)
+                (eq? style 'cross))
+           (stencil-whiteout (ly:note-head::print grob))
+           (ly:text-interface::print grob))))
+
+;; definitions for the "moderntab" clef:
+;; the "moderntab" clef will be added to the list of known clefs,
+;; so it can be used as any other clef: \clef "moderntab"
+(add-new-clef "moderntab" "markup.moderntab" 0 0 0)
+
+;; define sans serif-style tab-Clefs as a markup:
+(define-builtin-markup-command (customTabClef layout props num-strings staff-space)
+  (integer? number?)
+  music
+  ()
+  "Draw a tab clef sans-serif style."
+  (define (square x) (* x x))
+  (let* ((scale-factor (/ staff-space 1.5))
+         (font-size (- (* num-strings 1.5 scale-factor) 7))
+         (base-skip (* (square (+ (* num-strings 0.195) 0.4)) scale-factor)))
+
+        (interpret-markup layout props
+           (markup #:vcenter #:bold
+                   #:override (cons 'font-family 'sans)
+                   #:fontsize font-size
+                   #:override (cons 'baseline-skip base-skip)
+                   #:left-align #:center-column ("T" "A" "B")))))
+
+;; this function decides which clef to take
+(define-public (clef::print-modern-tab-if-set grob)
+  (let ((glyph (ly:grob-property grob 'glyph)))
+       ;; which clef is wanted?
+       (if (string=? glyph "markup.moderntab")
+           ;; if it is "moderntab", we'll draw it
+           (let* ((staff-symbol (ly:grob-object grob 'staff-symbol))
+                  (line-count   (ly:grob-property staff-symbol 'line-count))
+                  (staff-space  (ly:grob-property staff-symbol 'staff-space 1)))
+                 (grob-interpret-markup grob (make-customTabClef-markup line-count staff-space)))
+           ;; otherwise, we simply use the default printing routine
+           (ly:clef::print grob))))
+
+;; if stems are drawn, it is nice to have a double stem for
+;; (dotted) half notes to distinguish them from quarter notes:
+(define-public (tabvoice::draw-double-stem-for-half-notes grob)
+  (let ((stem (ly:stem::print grob)))
+
+       ;; is the note a (dotted) half note?
+       (if (= 1 (ly:grob-property grob 'duration-log))
+           ;; yes -> draw double stem
+           (ly:stencil-combine-at-edge stem X RIGHT stem 0.5)
+           ;; no -> draw simple stem
+           stem)))
+
+;; as default, the glissando line between fret numbers goes
+;; upwards, here we have a function to correct this behavior:
+(define-public (glissando::calc-tab-extra-dy grob)
+  (let* ((original (ly:grob-original grob))
+         (left-bound (ly:spanner-bound original LEFT))
+         (right-bound (ly:spanner-bound original RIGHT))
+         (left-pitch (ly:event-property (event-cause left-bound) 'pitch))
+         (right-pitch (ly:event-property (event-cause right-bound) 'pitch)))
+
+    (if (< (ly:pitch-semitones right-pitch) (ly:pitch-semitones left-pitch))
+        -0.75
+         0.75)))
+
+;; for ties in tablature, fret numbers that are tied to should be invisible,
+;; except for 'tied to' numbers after a line break;; these will be
+;; parenthesized (thanks to Neil for his solution):
+(define-public (parenthesize-tab-note-head grob)
+  ;; Helper function to parenthesize tab noteheads,
+  ;; since we can't use ParenthesesItem at this stage
+  ;; This is basically the same as the C++ function
+  ;; in accidental.cc, converted to Scheme
+  (let* ((font (ly:grob-default-font grob))
+         (open (stencil-whiteout
+                 (ly:font-get-glyph font "accidentals.leftparen")))
+         (close (stencil-whiteout
+                  (ly:font-get-glyph font "accidentals.rightparen")))
+         (me (ly:text-interface::print grob)))
+        (ly:stencil-combine-at-edge
+         (ly:stencil-combine-at-edge
+          me
+          X
+          LEFT
+          open)
+         X
+         RIGHT
+         close)))
+
+;; ParenthesesItem doesn't work very well for TabNoteHead, since
+;; the parentheses are too small and clash with the staff-lines
+;; Define a callback for the 'stencils property which will tweak
+;; the parentheses' appearance for TabNoteHead
+(define-public (parentheses-item::calc-tabstaff-parenthesis-stencils grob)
+   ;; the grob we want to parenthesize
+   (let ((victim (ly:grob-array-ref (ly:grob-object grob 'elements) 0)))
+     ;; check whether it's a notehead
+     (if (grob::has-interface victim 'note-head-interface)
+         (begin
+           ;; tweak appearance before retrieving
+           ;; list of stencils '(left-paren right-paren)
+           ;; get the font-size from victim (=TabNoteHead) to handle
+           ;; grace notes properly
+           (ly:grob-set-property! grob 'font-size
+                                  (ly:grob-property victim 'font-size))
+           (ly:grob-set-property! grob 'padding 0)
+           ;; apply whiteout to each element of the list
+           (map stencil-whiteout
+                (parentheses-item::calc-parenthesis-stencils grob)))
+         (parentheses-item::calc-parenthesis-stencils grob))))
+
+;; the handler for ties in tablature;; split ties yield in a parenthesized
+;; fret number, otherwise the fret number will be invisible.
+(define-public (tie::handle-tab-tie grob)
+   (let* ((original (ly:grob-original grob))
+          (tied-tab-note-head (ly:spanner-bound grob RIGHT))
+          (siblings (if (ly:grob? original)
+                        (ly:spanner-broken-into original) '())))
+
+     (if (and (>= (length siblings) 2)
+              (eq? (car (last-pair siblings)) grob))
+         ;; tie is split -> parenthesize
+         (ly:grob-set-property! tied-tab-note-head 'stencil
+                                (lambda (grob) (parenthesize-tab-note-head grob)))
+
+         ;; tie is not split -> make fret number invisible
+         (ly:grob-set-property! tied-tab-note-head 'transparent #t))))
+
+;; repeat ties occur within alternatives in a repeat construct;
+;; the correspondig fret numbers are shown in parentheses:
+(define-public (repeat-tie::parenthesize-tab-note-head grob)
+  (let ((tied-tab-note-head (ly:grob-object grob 'note-head)))
+
+        (ly:grob-set-property! tied-tab-note-head 'stencil
+                               (lambda (grob) (parenthesize-tab-note-head grob)))))
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