--- a/Slides/document/root.tex	Sat Jul 31 02:10:42 2010 +0100
+++ b/Slides/document/root.tex	Sun Aug 08 10:12:38 2010 +0800
@@ -109,12 +109,22 @@
 \chardef\isachardoublequoteclose=`\"%
 \chardef\isacharbackquoteopen=`\`%
 \chardef\isacharbackquoteclose=`\`%
+
+\let\oldisachardoublequoteopen=\isachardoublequoteopen
+\let\oldisachardoublequoteclose=\isachardoublequoteclose
+\let\oldisacharbackquoteopen=\isacharbackquoteopen
+\let\oldisacharbackquoteclose=\isacharbackquoteclose
+\newenvironment{innerdouble}%
+   {\oldisachardoublequoteopen \color{isacol:green}}%
+   {\color{isacol:black} \oldisachardoublequoteclose}
 \newenvironment{innersingle}%
-{\isacharbackquoteopen\color{isacol:green}}%
-{\color{isacol:black}\isacharbackquoteclose}
-\newenvironment{innerdouble}%
-{\isachardoublequoteopen\color{isacol:green}}%
-{\color{isacol:black}\isachardoublequoteclose}
+{\oldisacharbackquoteopen\color{isacol:green}}%
+{\color{isacol:black}\oldisacharbackquoteclose}
+
+\renewcommand{\isachardoublequoteopen}{\egroup\begin{innerdouble}\bgroup}
+\renewcommand{\isachardoublequoteclose}{\egroup\end{innerdouble}\bgroup}
+\renewcommand{\isacharbackquoteopen}{\egroup\begin{innersingle}\bgroup}
+\renewcommand{\isacharbackquoteclose}{\egroup\end{innersingle}\bgroup}
 
 %% misc
 \newcommand{\gb}[1]{\textcolor{isacol:green}{#1}}