If texcsstyle star used, opening (closing) square bracket(s) and the same one(s) with leading backslash indistinguishable as listings' delimiters

Question

The following MCE points out that, if used as listings' delimiters:

• [ and ] (opening and closing square brackets),
• \[ and \] (the same ones preceded with backslash),

cannot be distinguished (the order of the directives doesn't matter).

Update

As pointed out by Schweinebacke, it is enough to escape the backslash with a backslash. But this trick does not work if the optional star of texcsstyle is also used in order to highlight the backslash in front of the control sequence names. See the updated example.

Do you know:

1. why?
2. how make them distinguishable?

Subsidiary (but maybe related) question: how to color the whole \[ delimiter (currently, only [ is colored)?

\documentclass{article}
\usepackage{listings}
\usepackage{xcolor}
%
\lstset{
  language=[AlLaTeX]TeX, %
  basicstyle=\ttfamily,%
  moredelim=*[s][\color{blue}]{[}{]},%
  moredelim=*[s][\color{red}]{\\[}{\\]},%
}
%
\begin{document}

\begin{lstlisting}
\documentclass[fleqn]{article}
\usepackage{amsmath}
\begin{document}
\[x=0\]
\end{document}
\end{lstlisting}

\lstset{texcsstyle=*\color{green}}

\begin{lstlisting}
\documentclass[fleqn]{article}
\usepackage{amsmath}
\begin{document}
\[x=0\]
\end{document}
\end{lstlisting}

\end{document}

Answer 1

Problem of interaction of texcsstyle=*... option with moredelim option, from updated question, seems to be a separate issue, than missing backslash, from original question, solved already by answer of Schweinebacke.

Issue from update is similar to problem of interaction of texcsstyle=*... option with literate option, described in my answer to "lstlisting: color LaTeX commands like \\ or \!" question.

When tex aspect is loaded, it adds code, to SelectCharTable hook, that can override behavior of backslashes defined using other aspects. To restore proper behavior one can add relevant code to SelectCharTable hook after loading tex aspect. In case of moredelim option relevant code is \lst@DefDelims macro.

Full example of "rehooking" delimiters char table is:

\documentclass{article}
\usepackage{listings}
\usepackage{xcolor}

\lstset{
  language=[AlLaTeX]TeX, %
  basicstyle=\ttfamily,%
  texcsstyle=*\color{green},%
  moredelim=*[s][\color{blue}]{[}{]},%
  moredelim=*[s][\color{red}]{\\[}{\\]},%
}

% "Rehook" delimiters char table.
\makeatletter
\lst@AddToHook{SelectCharTable}{\lst@DefDelims}
\makeatother

\begin{document}

\begin{lstlisting}
\documentclass[fleqn]{article}
\usepackage{amsmath}
\begin{document}
\[x=0\]
\end{document}
\end{lstlisting}

\end{document}

Answer 2

\documentclass{article}
\usepackage{listings}
\usepackage{xcolor}
%
\lstset{%
  basicstyle=\ttfamily,%
  moredelim=*[s][\color{blue}]{[}{]},%
  moredelim=*[s][\color{red}]{\\[}{\\]},%
}
%
\begin{document}
\begin{lstlisting}
\documentclass[fleqn]{article}
\usepackage{amsmath}
\begin{document}
\[x=0\]
\end{document}
\end{lstlisting}
\end{document}

You need this extra backslash for {, }, #, % and \. See note 5 in section 4.1 of the listings manual.