[XeTeX] abraces and unicode-math

[Daniel Greenhoe]

Using \underbrace with the unicode-math package In the TeXLive 2012
distribution produces sporadic errors. It has been stated that
underbraces are handled by the engine and that a fix will not be
available until the release of TeXLive 2013.

However, in the meantime, could someone help me maybe get a macro
patch working that is compatible with unicode-math?

I was thinking that maybe the abraces package from Werner Grundlingh
could be used. The problem is, abraces does not currently seem to be
compatible with unicode-math. I tried to fix this by redefining some
variables, but it didn't work out (it produces garbage results).

\documentclass[oneside]{book}
%
\usepackage{unicode-math}            % unicode math support
\setmathfont{xits-math.otf}
%\setmathfont{Asana-math.otf}
%\setmathfont{latinmodernmath-regular.otf}
%\setmathfont{texgyrepagellamath-regular.otf}
%\setmathfont{texgyretermesmath-regular.otf}
%\setmathfont{xits-regular.otf}
\usepackage[overload]{abraces}
\XeTeXmathchardef\bracelu  = 0 3 "23A7
\XeTeXmathchardef\bracemu  = 0 3 "23A8
\XeTeXmathchardef\braceru  = 0 3 "23A9
\XeTeXmathchardef\bracebar = 0 3 "23AA
\XeTeXmathchardef\braceld  = 0 3 "23AB
\XeTeXmathchardef\bracemd  = 0 3 "23AC
\XeTeXmathchardef\bracerd  = 0 3 "23AD
\begin{document}%
\[ \underbrace{\sin^2x+\cos^2x=1} \]
\[ \underbrace{\sin^2x+\cos^2x=1} \]
\[ \underbrace{\sin^2x+\cos^2x=1} \]
...
\end{document}

Does anyone have a solution? A source file and output file is attached.

Many thanks in advance,
Dan
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