\chapter* chapter name customisation in fncychap glenn

Question

I'm currently writing a book and I've decided to use the fncychap glenn style for my chapter headings. It's working great, but I was wondering if there's a way I could change the chapter name (eg. Chapter 1) in the top left hand corner to "Prologue".

\documentclass[openany]{book}
\usepackage[Glenn]{fncychap}

\begin{document}

\chapter*{Prologue}
\chapter{Redundant Chapter}

\end{document}

So, in the case of what's above, where it says CHAPTER 1, I would like to say 'PROLOGUE', leaving the bottom open for whatever else I want (unconventional, I know. But it's in case I have other stuff I want to put in there later). I have an idea that I'd need to overwrite the \chNameVar but I'm not entirely sure of how to do it. Any help would be greatly appreciated!

Answer 1

Like this?

\documentclass[openany]{book}
\usepackage[Glenn]{fncychap}
\makeatletter
%\ChNameVar{\Large\rmfamily}   %% earlier \Large\rm
%\ChNumVar{\Large}          %% earlier \Huge
%\renewcommand{\@chapapp}{Prologue}
\renewcommand{\DOTIS}[1]{%
    \setlength{\py}{20pt}
    \setlength{\pyy}{\py}
    \setlength{\backskip}{\py}
    \addtolength{\backskip}{2pt}
    \addtolength{\pyy}{\RW}
    \setlength{\myhi}{\baselineskip}
    \addtolength{\myhi}{\pyy}
    \vskip 0.9\pyy
    {\Large\sffamily\MakeUppercase{ Prologue}}\space\mghrulefill{\RW}\rule[-1\py]{2\RW}{\pyy}\par\nobreak
    \vskip -0.8\backskip
    \rule{2\RW}{\myhi}\mghrulefill{\RW}\hskip 3pt %
    \raggedleft\CTV\FmTi{#1}\par\nobreak
    \vskip 40\p@}
\makeatother

\begin{document}

\chapter*{Prologue}
\chapter{Redundant Chapter}

\end{document}