mdframed and parskip

Question

This seems pretty easy: how can I get a paragraph skip in an mdframed, same as outside the box? Is it somehow `disabled', and if so, is there a reason for that?

Here is how it's set up, in a floating environment. Don't know if that does anything; I copied and modified the code from another post, so I don't totally know how it works.

\documentclass{report}
\usepackage{geometry}
\usepackage[parfill]{parskip} 
\usepackage[framemethod=TikZ]{mdframed}
\mdfsetup{frametitlealignment=\center}
\usepackage{newfloat}

\DeclareFloatingEnvironment[fileext=frm,placement={!ht},name=Frame]{myfloat}
\newenvironment{infobox}[2][ht] {
   \begin{myfloat}[#1]
        \begin{mdframed}[roundcorner=10pt,frametitle={Box~X: #2},nobreak=false]}
    {\end{mdframed}\end{myfloat}}


\begin{document}

\chapter{}
Hello, this is text.

Using parskip with parfill option.

\begin{infobox}{Title}
Why does this not have line skips?

I would like it to look like the rest of the document.
\end{infobox}

\end{document}

Sorry if this is a duplicate of another question, but if so I couldn't find it.

Answer 1

As mentioned above in the comments, this seems to be related to some ad hoc choice of the creator of LaTeX. Here is a possible workaround.

\documentclass{report}
\usepackage{geometry}
\usepackage[parfill]{parskip} 
\usepackage{tikz}
\usetikzlibrary{backgrounds}
\usepackage{tikzpagenodes}
\usepackage{lipsum}
\tikzset{SimpleBox/.style={draw,thick,rounded corners}}


\newcommand{\SimpleBox}[2][2pt]{%
\tikz[remember picture,overlay, baseline=(Begin.base)]{%
\node[anchor=base,inner sep=0pt,outer sep=0pt] (Begin) {\strut};}#2%
\tikz[remember picture,overlay, baseline=(End.base)]{%
\node[anchor=base,inner sep=0pt,outer sep=0pt] (End) {\strut};}%
\begin{tikzpicture}[overlay,remember picture]
\path (current page text area.north west) -- (current page text area.south west)
node(WestLine)[left]{};
\path (current page text area.north east) -- (current page text area.south east)
node(EastLine)[right]{};
\begin{scope}[on background layer]
\draw[SimpleBox] (Begin.north-|WestLine) rectangle (End.south-|EastLine);
\end{scope}
\end{tikzpicture}}

\begin{document}

Hello, this is text.

Using parskip with parfill option.


\SimpleBox{
\centerline{\textbf{Box X: Title}}
Hello, this is text.

Using parskip with parfill option also works in the box (and not just ``out of
the box'';-).
}


\end{document}

I understand that this does not answer your question, but I hope it allows you to achieve an output similar to what you wanted.

ADDENDUM: A code that allows the box to run over one (!) page break. Relies on the pioneering work of this post.

\documentclass{report}
\usepackage{geometry}
\usepackage[parfill]{parskip} 
\usepackage{refcount}
\usepackage{tikz}
\usetikzlibrary{backgrounds}
\usepackage{tikzpagenodes}
\usepackage{lipsum}
\newif\ifSimpleBoxOpen\SimpleBoxOpentrue
\tikzset{SimpleBox/.style={draw,thick,rounded corners}}

\usepackage{lipsum}
\newcounter{tmp}
\newcommand\tikzmark[1]{%
  \tikz[overlay,remember picture] \node (#1) {};}

\newcommand\StartBox[1][]{%
  \stepcounter{tmp}%from https://tex.stackexchange.com/a/52579/121799
  \tikz[remember picture,overlay, baseline=(Begin.base)]{%
  \node[anchor=base,inner sep=0pt,outer sep=0pt] (Begin) {\strut};}
  \label{a\thetmp}%
  \ifnum\getpagerefnumber{a\thetmp}=\getpagerefnumber{b\thetmp} \else
  \begin{tikzpicture}[overlay, remember picture]
   \path (current page text area.north west) -- (current page text area.south west)
    node(WestLine)[left]{};
   \path (current page text area.north east) -- (current page text area.south east)
    node(EastLine)[right]{};
   \begin{scope}[on background layer,blend mode=multiply]
   \ifSimpleBoxOpen
   \draw[SimpleBox,#1] ( current page text area.south-|WestLine) -- 
   (Begin.north-|WestLine) -- (Begin.north-|EastLine) --  (current page text
   area.south-|EastLine);
   \else
   \draw[SimpleBox,#1] (Begin.north-|WestLine) rectangle (current page text
   area.south-|EastLine);
   \fi
   \end{scope}
  \end{tikzpicture}%
  \fi%
}

\newcommand\EndBox[1][]{%
\tikz[remember picture,overlay, baseline=(End.base)]{%
\node[anchor=base,inner sep=0pt,outer sep=0pt] (End) {\strut};}%
  \label{b\thetmp}
  \ifnum\getpagerefnumber{a\thetmp}=\getpagerefnumber{b\thetmp}
  \begin{tikzpicture}[overlay,remember picture]
   \path (current page text area.north west) -- (current page text area.south west)
    node(WestLine)[left]{};
   \path (current page text area.north east) -- (current page text area.south east)
    node(EastLine)[right]{};
   \begin{scope}[on background layer]
    \draw[SimpleBox,#1] (Begin.north-|WestLine) rectangle (End.south-|EastLine);
   \end{scope}
  \end{tikzpicture}
  \else
  \begin{tikzpicture}[overlay,remember picture]
   \path (current page text area.north west) -- (current page text area.south west)
    node(WestLine)[left]{};
   \path (current page text area.north east) -- (current page text area.south east)
    node(EastLine)[right]{};
   \begin{scope}[on background layer,blend mode=multiply]
   \ifSimpleBoxOpen
   \draw[SimpleBox,#1] ( current page text area.north-|WestLine) -- 
   (End.south-|WestLine) -- (End.south-|EastLine) --  (current page text
   area.north-|EastLine);
   \else
   \draw[SimpleBox,#1] (Begin.north-|WestLine) rectangle (current page text
   area.south-|EastLine);
   \fi
   \end{scope}
  \end{tikzpicture}
  \fi
}

\newcommand{\SimpleBox}[2][]{%
\StartBox[#1]%
#2\EndBox[#1]}

\begin{document}

Hello, this is text.

Using parskip with parfill option.


\SimpleBox{
\centerline{\textbf{Box X: Title}}
Hello, this is text.

Using parskip with parfill option also works in the box (and not just ``out of
the box'';-).
}

\lipsum[1-4]

\SimpleBox{\lipsum[5-6]}

\end{document}