Tikz: How to move a footnote in a node out of that group?

Question

Apologies for the slightly strange title, I struggled to come up with something else.

I have defined my own quote environment with brackets around the quote. In order to do that I use tikz and the quote content is put in a node. If I now use a \footnote in this node it is but directly under the quote. I'd rather have the footnote at the end of the page, so how can I "break out" of the local group the tikz node seems to create?

\documentclass[parskip=half]{scrartcl}

\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{environ,xcolor}
\usepackage{lipsum}

\NewEnviron{bquote}{%
\noindent%
\par%
\addmargin{30pt}
\begin{tikzpicture}%
\node[text width=0.97\linewidth](q){\BODY};%
\draw[ultra thick,line width=7pt,overlay,gray!30] (q.north west) -- ($(q.north
west) - (15pt,0)$) -- ($(q.south west) - (15pt,0)$) -- (q.south west);%
\draw[ultra thick, line width=7pt,overlay,gray!30] (q.north east) -- ($(q.north
east) + (15pt,0)$) -- ($(q.south east) + (15pt,0)$) -- (q.south east);% 
\end{tikzpicture}%
\footnote{Outside the group}%just a test
\par%
}%

\begin{document}
 \lipsum[1]
\begin{bquote}
\lipsum[3]\footnote{Inside the node and sadly local}
\end{bquote}
\lipsum[1]
\end{document}

Answer 1

You can use the footnote package and wrap the tikzpicture in a savenotes environment. This stores all internal footnotes which otherwise are collected by the internal minipage TikZ uses for \node [text width=<length>].

Here the code with some other improvements:

\documentclass[parskip=half]{scrartcl}

\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{xcolor}
\usepackage{footnote}
\usepackage{lipsum}

\newenvironment{bquote}{%
\par%
\noindent%
\addmargin{30pt}%
\begin{savenotes}%
\begin{tikzpicture}%
\node[text width=0.97\linewidth](q)\bgroup
}{%
\egroup;%
\draw[ultra thick,line width=7pt,overlay,gray!30] (q.north west) -- ($(q.north
west) - (15pt,0)$) -- ($(q.south west) - (15pt,0)$) -- (q.south west);%
\draw[ultra thick, line width=7pt,overlay,gray!30] (q.north east) -- ($(q.north
east) + (15pt,0)$) -- ($(q.south east) + (15pt,0)$) -- (q.south east);% 
\end{tikzpicture}%
\end{savenotes}%
\footnote{Outside the group}%just a test
\par%
}%

\begin{document}
 \lipsum[1]
\begin{bquote}
\lipsum*[3]\footnote{Inside the node and sadly local} bla bla
\end{bquote}
\lipsum[1]
\end{document}

Answer 2

As I understand it from other questions, TikZ creates a minipage for nodes, so that explains why the footnote gets put inside the node. To get the other behavior you want, you can try using \footnotemark at the point you want the footnote to appear, then use \footnotetext{the text of the note} outside the environment so that it appears at the bottom of the page.

You could also try automating the process:

\def\pendingfootnotes{}
\let\ex\expandafter
\newcommand\externfootnote[1]{%
  \ex\global\ex\def\ex\pendingfootnotes\ex{\ex\pendingfootnotes\footnotetext{#1}}%
  \footnotemark%
}

and at the very end of your environment add

\pendingfootnotes
\global\def\pendingfootnotes{}

to insert them at the end. I use "externfootnote" so that if you still want the "normal" \footnote behavior, it's still available. I think you need the \global to ensure the changes propagate outside the TikZ environment, but I may be wrong...