Tikz node and nonalphanumeric characters

Question

I cannibalised some code from the thread Simple speech bubbles, arrows or balloon like shapes in beamer. It works really well, but crashes whenever non-alphanumeric characters are used in the node. Here's the code

\newcommand{\callouts}[3]{\tikz[remember picture,baseline]{\node[anchor=base,inner sep=0,outer sep=0]%
    (#3){\colorbox{#1!20}{#3}};\node[overlay,rectangle callout,%
    callout relative pointer={(0cm,0.5cm)},fill=#1!20] at ($(#3.south)+(-0cm,-0.7cm)$){#2};}%
    }%

And this is what it creates;

However, when I try to highlight and label a string with a non-alphanumeric character, e.g. comma or a mathematical symbol, the command crashes. I've tried using math mode and the \text{} command, but neither of these work. Any pointers appreciated.

Answer 1

The problem is that the string that is used for the label contents of the node is also used also to provide a name for the node and this can cause problems; the solution is to use another (simpler) string for naming the node; in the following example I use a counter to provide the name for the nodes:

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{calc,shapes.callouts,shapes.arrows}

\newcounter{mycallout}

\newcommand{\callouts}[3]{%
  \stepcounter{mycallout}
  \tikz[remember picture,baseline]{\node[anchor=base,inner sep=0,outer sep=0]%
    (\themycallout) {\colorbox{#1!20}{#3}};\node[overlay,rectangle callout,%
    callout relative pointer={(0cm,0.5cm)},fill=#1!20] at ($(\themycallout.south)+(-0cm,-0.7cm)$){#2};}%
    }%

\begin{document}

\callouts{blue}{text;$a\neg$}{text,$a\neg$}

\end{document}