I want to send a dissertation document with chapterthumbs to the printing house. The document is written in KOMA-Script and a good solution for bleed correction is found here. Since chapterthumbs are sitting at the edge of the pages in black I want to make sure that there is a bleed correction for that too before sending out the document. Otherwise, due to imprecise cutting process (which is expected), unwanted white margins could appear at the edge of the pages where chapterthumbs are sitting.
Question
How to provide a bleed correction for the chapterthumbs themselves, i.e. extend their black color to the bleed correction area as in the image below?
Output
Consider the MWE below, where chapterthumbs are provided and bleed correction using crop package. What is missing is bleed correction for the chapterthumbs themselves.
MWE Code
\documentclass[paper=a4, twoside=semi]{scrbook} % A4 is 210mm x 297mm
\usepackage[cross,center,width=216mm,height=303mm]{crop} % bleed is 6mm
\usepackage{blindtext}
\usepackage{calc}%
\usepackage{chapterthumb}% package should be installed in the same active folder
\usepackage{etoolbox}%
\usepackage{nameref}%
\usepackage{totcount}
\regtotcounter{chapter}%
%=====================Bibliography=============================
\usepackage{biblatex}
\usepackage{filecontents}
\begin{filecontents}{jobname.bib}
@article{rand_objective_1971,
title = {Objective criteria for the evaluation of clustering methods},
volume = {66},
pages = {846},
number = {336},
journaltitle = {Journal of the American Statistical Association},
author = {Rand, William M.},
date = {1971}
}
\end{filecontents}
\addbibresource{jobname.bib}
%=========================Chapter thumbs========================
\AtBeginDocument{%
\ifnumequal{\number\totvalue{chapter}}{0}{%
\renewcommand{\chapterthumbwidth}{\paperheight}%
\renewcommand{\chapterthumbskip}{\paperheight}%
}{%
\typeout{There are \number\totvalue{chapter} chapter in this document}%
\renewcommand{\chapterthumbskip}{\paperheight/\number\totvalue{chapter}}%
\renewcommand{\chapterthumbwidth}{\paperheight/\number\totvalue{chapter}}%
}%
}%
\lohead[\putchapterthumb]{\putchapterthumb}
\addtokomafont{chapterthumb}{\bfseries}
\newrobustcmd{\SetChapterThumbHeader}{%
\lohead[\putchapterthumb]{\putchapterthumb}%
}%
\newrobustcmd{\ClearChapterThumbHeader}{%
\lohead[]{}%
}%
\newrobustcmd{\refcommand}[1]{%
\nameref*{#1}%
}%
\newtoggle{UseChapterThumb}%
\toggletrue{UseChapterThumb}%
\renewcommand*{\chapterthumbformat}{\refcommand{chapter::title::\number\value{chapter}}}%
\makeatletter
\newcounter{totalchaptercounter}%
\newrobustcmd{\CreateUniqueChapterLabel}[1]{%
\refstepcounter{totalchaptercounter}%
\label{chapter::title::\number\value{totalchaptercounter}}%
}%
\let\LaTeXStandardChapter\chapter%
\newcommand{\chapter@noopt}[1]{%
\iftoggle{UseChapterThumb}{\SetChapterThumbHeader}{\ClearChapterThumbHeader}
\LaTeXStandardChapter{#1}%
\CreateUniqueChapterLabel{#1}%
}%
\newcommand{\chapter@opt}[2][]{%
\iftoggle{UseChapterThumb}{\SetChapterThumbHeader}{\ClearChapterThumbHeader}
\LaTeXStandardChapter[#1]{#2}%
\CreateUniqueChapterLabel{#2}% Must appear after chapter title is done
}%
\newcommand{\unstarredchapter}{%
\@ifnextchar[{\chapter@opt}{\chapter@noopt}%
}%
\newcommand{\starredchapter}[1]{%
\ClearChapterThumbHeader% Clear the headers -> no chapterthumb here
\LaTeXStandardChapter*{#1}%
}%
\renewcommand{\chapter}{%
\@ifstar{\starredchapter}{\unstarredchapter}%
}%
\let\LaTeXStandardTOC\tableofcontents%
\renewcommand{\tableofcontents}{%
\begingroup%
\renewcommand{\chapter}{\LaTeXStandardChapter}%
\LaTeXStandardTOC%
\endgroup%
}%
\let\LaTeXStandardLOF\listoffigures%
\renewcommand{\listoffigures}{%
\begingroup%
\renewcommand{\chapter}{\LaTeXStandardChapter}
\LaTeXStandardLOF%
\endgroup
}%
\let\LaTeXStandardLOT\listoftables%
\renewcommand{\listoftables}{%
\begingroup%
\renewcommand{\chapter}{\LaTeXStandardChapter}
\LaTeXStandardLOT%
\endgroup
}%
\let\LaTeXStandardPrintBibliography\printbibliography%
\newrobustcmd{\commonprintbibliographysetup}[1][]{%
\iftoggle{UseChapterThumb}{\SetChapterThumbHeader\refstepcounter{chapter}}{\ClearChapterThumbHeader}
\LaTeXStandardPrintBibliography[#1]
\iftoggle{UseChapterThumb}{%
\immediate\write\@auxout{%
\string\newlabel{chapter::title::\number\value{chapter}}{{\thepage}{\thepage}{Bibliography}{}}%
}%
}{}%
}%
\newrobustcmd{\printbibliography@@noopt}{%
\commonprintbibliographysetup[]%
}%
\newrobustcmd{\printbibliography@@opt}[1][]{%
\commonprintbibliographysetup[#1]%
}
\renewcommand{\printbibliography}{%
\@ifnextchar[{\printbibliography@@opt}{\printbibliography@@noopt}%
}%
\makeatother
%==================================================
\title{Title of the Dissertation}
\author{Author Name}
\publishers{Faculty Name}
\begin{document}
\maketitle
\pagestyle{plain}
\pagenumbering{roman}
\tableofcontents
\listoffigures
\listoftables
\cleardoublepage
\chapter*{Acknowledgments}
\addcontentsline{toc}{chapter}{Acknowledgments}
\chapter*{Abstract}
\addcontentsline{toc}{chapter}{Abstract}
\cleardoublepage
\lohead[\putchapterthumb]{\putchapterthumb}
\mainmatter
\pagestyle{scrheadings}
\chapter{Introduction}
\begin{figure}
\caption{dummy figure}
\end{figure}
\chapter{Materials \& Methods}
\chapter{Results}
\begin{table}
\caption{dummy table}
\end{table}
\chapter{Discussion}
In his reference \parencite{rand_objective_1971}, the author did a nice job.
\backmatter
\cleardoublepage
\printbibliography[heading=bibintoc]
\end{document}
Update1: MWE based on Symbol's solution
I wonder what might cause this inequality in the crosses.
and 
.
frameoption, i.e.\usepackage[...,frame]{crop}http://tex.stackexchange.com/questions/65170/what-is-bleed-and-how-do-i-achieve-it