Manual Chapter 2.10.2 Arabic music subchapter Selected Snippets Non-traditional key signatures

[Blöchl Bernhard]

\include "arabic.ly"
\relative do' {
  \set Staff.keyAlterations = #`(
    (0 . ,SEMI-FLAT)
    (1 . ,SEMI-FLAT)
    (2 . ,FLAT)
    (5 . ,FLAT)
    (6 . ,SEMI-FLAT)
  )
  %\set Staff.extraNatural = ##f
  re reb \dwn reb resd
  dod dob dosd \dwn dob |
  dobsb dodsd do do |
}

The key accidentals in this example are shown in the turkish notation 
version. Is there any chance to get the key accidentals in the arabic 
view with the slashed half accidental, as with

dwn = {
  \once \override Voice.Accidental.stencil = #(lambda (grob)
  (ly:stencil-combine-at-edge
    (ly:accidental-interface::print grob) Y UP
    (grob-interpret-markup grob (markup #:line
          (#:fontsize -1 (#:musicglyph "flags.ugrace")))) -1.3))
}