add dottedExtender

basic_format_and_style_settings.ly

@@ -193,4 +193,22 @@ updown =
     \tag #'up { \markup { #(string-capitalize word) } }
     \tag #'down { \markup { #(string-downcase word) } }
   }
-#})
+#})
+
+dottedExtender = {
+  \override LyricExtender.style = #'dotted-line
+  \override LyricExtender.thickness = 2
+  \override LyricExtender.Y-offset = 0.1
+  \override LyricExtender.stencil =
+    #(lambda (grob)
+      (let* ((stil (ly:lyric-extender::print grob))
+             (nostil (null? stil))
+             (x-ext (if nostil 0 (ly:stencil-extent stil X))))
+         (if nostil
+           stil
+           (make-connected-line
+             (list
+               (cons (car x-ext) 0)
+               (cons (cdr x-ext) 0))
+             grob))))
+}