I am trying to draw a circle around a bunch of nodes in a flow chart that I've created using beamer and I can't figure out how to do it. Ideally, I'd like the circle to encompass most (but not all of the nodes). How do I do this?
Here is my code:
\begin{frame}
\frametitle{The Regime Complex for Climate Change\\(Keohane and Victor (2011) )}
\tikzstyle{type1} = [rectangle, rounded corners, minimum width=3cm, minimum height=0.1cm,text centered, draw=black, fill=blue!10, text width=2cm]
\tikzstyle{type2} = [rectangle, rounded corners, minimum width=3cm, minimum height=0.1cm, text centered, draw=black, fill=blue!10, text width=5cm]
\tikzstyle{info} = [rectangle, rounded corners, minimum width=2.5cm, minimum height=0.1cm, text centered, draw=black,
fill=blue!30, text width=2.5cm]
\tikzstyle{org} = [rectangle, rounded corners, minimum width=2cm, minimum height=0.1cm, text centered, draw=black,
fill=blue!30, text width=3cm]
\tikzstyle{decision} = [square, minimum width=1cm, minimum height=0.1cm, text centered,
draw=black, fill=green!30, text width=4cm]
\tikzstyle{arrow} = [thick,->,>=stealth]
\begin{tikzpicture}[node distance=1.2cm]
\node (un) [type1, xshift=-3cm] {UN Legal Regimes};
\node (expert) [type1, right of=un, xshift=4cm]{Expert Assessments};
\node (montreal)[type1, below of=un, xshift=-1cm]{Montreal Protocol};
\node (bilateral)[type1, right of=montreal, xshift=3cm]{Bilateral Initiatives};
\node (clubs)[type1, right of=bilateral, xshift=2cm]{Clubs};
\node(subnat)[type1, below of=montreal, xshift=1cm]{Subnational Action};
\node(MDA)[type1, right of=subnat, xshift=4cm]{MDA};
\node(geo)[type1, below of=subnat, xshift=-1cm]{Geoengineering Governance};
\node(nuc)[type1, right of=geo, xshift=2cm]{Nuclear Technology};
\node(fin)[type1, right of=nuc, xshift=2cm]{Financial Market Rules};
\node(intel)[type2, below of=geo, xshift=1cm]{Intel Property and Investment Rules};
\node(trade)[type2, right of=intel, xshift=5cm]{International Trade Regime};
\end{tikzpicture}
\end{frame}

{}it will be highlighted as you see above. (Edit: I also added a missing semicolon after the last node.) – Torbjørn T. Nov 27 '13 at 19:47