LilyPond - Adding dotted lines to "Table of Contents" TOC

Question

I posted a question on here about two different coding techniques on how to add a table of contents to a LilyPond Book. I am kind of stuck with the solution in the first example, since it gives me the possibility to add multiple table of contents into my book.

---

First Example (without dotted line):

#(define-markup-command (toc-line layout props label text)
  (symbol? markup?)
  (interpret-markup layout props
   (markup #:fill-line (text #:page-ref label "8" "?"))))

%Table of Contens
\label #'toc
\markup {
  \column {
    \large \fill-line { \null \bold \italic "Table Of Contents" \null }
    \toc-line #'toc "Table Of Contents"
    \toc-line #'firstPart "First Score"
    \toc-line #'secondPart "Second Score"
  }
}

\label #'firstPart
\label #'secondPart

(Reference: taken from the LilyPond Documetory)

---

Second Example (with dotted line):

\header { tagline = ##f }
\paper {
  tocItemMarkup = \tocItemWithDotsMarkup
}

\book {
  \markuplist \table-of-contents
  \tocItem \markup { Allegro }
  \tocItem \markup { Largo }
  \markup \null
}

(Reference: taken from the LilyPond Documetory)

---

My question is: How do I add dotted lines using the code in the first example, so I would get an output with dotted lines as shown in the second example?

I can draw a dotted line like this using a postscript:

\markup {
  \postscript #"0.3 setlinewidth 1 setlinecap [0 1] 0 setdash 1 1 moveto 60 0 rlineto stroke"
}

How can I add this postscript to fill the space between the text and the page number in the toc definition of the first example?

#(define-markup-command (toc-line layout props label text)
      (symbol? markup?)
      (interpret-markup layout props
       (markup #:fill-line (text #:page-ref label "8" "?"))))

---

This Project can be found here on GitHub.com