定义练习并使用一些宏时tcolorbox，我注意到，如果我将宏插入到tcolorbox用 生成的练习中tcolorbox，则该breakable选项不起作用，因此框不会损坏。如何使此选项对这种“框中框”的情况有效？
我给出了我的文件的 MWE .tex，其中可以看到第 1、2、3 页中的盒子破损了，而第 4 页中的盒子却拒绝破损：
\documentclass{book}
\usepackage[most]{tcolorbox}
\tcbuselibrary{skins,breakable}
\usepackage{polyglossia}
\setmainlanguage[numerals=maghrib]{arabic}
\setotherlanguage{english}
\usepackage{fontspec}
\setmainfont{Times New Roman}
\setsansfont{Arial}
\setmonofont{Courier New}
\newfontfamily{\arabicfont}[Script=Arabic,Scale=1.5]{Traditional Arabic}
\usepackage{polyglossia}
\setdefaultlanguage{arabic}
\newcounter{example}[section]
\renewcommand{\theexample}{\arabic{example}}
\newcommand{\examplelabel}{%
{\bfseries\large
Ex.
\LR{\theexample}
}}
\newtcolorbox[use counter=example]{example}[1][]{enhanced jigsaw,breakable,
colback=white, colframe=red, arc=0mm,
rightrule=0mm, leftrule=0mm,toprule=0mm,
top=1mm, bottom=1mm, left=0mm, right=0mm,
colbacktitle=green, coltitle=black,
title=#1,
extrude right by=-5.5mm,
before upper={\parshape 4
0pt \dimexpr \hsize-7mm\relax
0pt \dimexpr \hsize-7mm\relax
0pt \dimexpr \hsize-7mm\relax
0pt \hsize},
code={\ifstrempty{#1}{}{%
\tcbset{
before upper={\parshape 3
0pt \dimexpr \hsize-7mm\relax
0pt \dimexpr \hsize-7mm\relax
0pt \hsize},
}}},
underlay unbroken and first={%
\node[fill=yellow, draw=red, line width=1.5pt, below right, minimum height=3em, text width=.8cm, align=center] at ([xshift=-.1mm]frame.north east) {\examplelabel};
\draw [red,line width=.5mm]([yshift=.25mm]frame.north west)--+(\linewidth,0);
},
underlay unbroken and last={%
\draw [red,line width=.5mm]([yshift=.25mm]frame.south west)--+(\linewidth,0);
},
}
\tikzstyle{titlewhite} =
[draw=black, thick, scale=.9, fill=white,%
line width=0.3pt, text=black, rectangle,
font=\normalsize,
left, minimum height=.5cm]
\newenvironment{blankbox}[2][]{%
\begin{tcolorbox}[enhanced jigsaw,breakable,
colback=white, colframe=white, arc=0mm,
top=0mm, bottom=0mm, left=2mm, right=2mm,
colframe=black,
top=5mm,
%bottom=6mm,
enlarge top by=\baselineskip/2+1mm,
enlarge top at break by=0mm,pad at break=2mm,
fontupper=\normalsize,
overlay unbroken and first={%
\node[titlewhite]
at ([xshift=-1cm]frame.north east)
{\large \RL{#2}};},
before=\par\smallskip\centering,
coltitle=black,
fonttitle=\large,%%fontupper=\large,
rightrule=0mm,
borderline east={0pt}{0pt}{white},
leftrule=0.2mm,toprule=0.2mm,bottomrule=0.2mm,
]}{%
\end{tcolorbox}}
\begin{document}
\noindent
\LR{
In this document, the text would be written in arabic, a right-to-left language
}
\begin{example}[\hspace*{2.5mm}\LR{A broken example}]
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
%%\vspace*{10cm}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\end{example}
\begin{blankbox}{\LR{A broken box}}
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
%%\vspace*{10cm}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\end{blankbox}
\begin{example}[\hspace*{2.5mm}\LR{A non-broken example}]
\vspace*{5mm}
\begin{blankbox}{Title}
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
\\
\LR{
An example artificially broken
}
%%\vspace*{10cm}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
}
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
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\LR{
An example artificially broken
}
\end{blankbox}
\end{example}
\end{document}
它是用 xelatex 编译的：
答案1
引用tcolorbox手册（当前版本 4.15 第 365 页）：
您可以将一个不可破坏的 tcolorbox 嵌套在另一个 tcolorbox 中，甚至可以嵌套在可破坏的 tcolorbox 中。但您不能将可破坏的框嵌套在可破坏的框中。嵌套框的 /tcb/breakable 键会自动忽略，即内部框始终是不可破坏的。
毕竟，在极少数情况下，您确实希望嵌套框可破坏，请对嵌套框使用 /tcb/enforce breakable。但是，可破坏框套在可破坏框中通常会造成混乱。
所以即使有enforce breakable选择，这也是不可取的。（我在其他场合也尝试过，结果真的很混乱）
更新 2019/02/15
文中仍然保留了（最有可能的）错误措辞“不能不”。