parbox=false not working in posterbox

Question

tcolorbox internally uses parbox or minipages which means it does not respect paragraph spacing from parskip package. This can be changed by passing a parbox=false to a tcolorbox which forces it to follow normal formatting. However the option does not seem to work when using tcbposter and posterboxs.

MVE:

\documentclass{article}
\usepackage[poster]{tcolorbox}
\usepackage{lipsum}
\usepackage{parskip}

\begin{document}

\begin{tcolorbox}[parbox=false]
\lipsum[1]

\lipsum[2]
\end{tcolorbox}

\begin{tcbposter}[coverage={spread downwards},poster={columns=1, rows=1},boxes={parbox=false}
]

\posterbox[adjusted title=Foo] {column=1, row=1}
{
\lipsum[1]

\lipsum[2]
}

\lipsum

\end{tcbposter}

\end{document}

produces the result below where the normal tcolorbox with parbox=false has paragraph spacing but the poster one doesn't. I noticed that if I remove the coverage option the problem goes away, but I can't understand what the link is:

Answer 1

parbox=false is described as an experimental feature in the manual. Instead you can just use before upper to reinsert the parskip code:

\documentclass{article}

\usepackage[poster]{tcolorbox}
\usepackage{lipsum}
\usepackage{parskip}

\begin{document}

\begin{tcbposter}[coverage={spread downwards},
  poster={columns=1, rows=1},
  boxes={before upper={\parskip.5\baselineskip%
  \advance\parskip 0pt plus 2pt}}]

\posterbox[adjusted title=Foo] {column=1, row=1}
{
\lipsum[1]

\lipsum[2]
}
\end{tcbposter}

\end{document}