[luatex] Correct use of \overwithdelims?

[Will Robertson]

Hi,

We're in territory in which I'm a little unfamiliar, so please excuse 
the questions. What is the correct way to use \overwithdelims with 
LuaTeX?

In Plain and XeTeX, the brackets enlarge satisfactorily (see attached 
example), based on (so I read) fontdimens 20 & 21. In LuaTeX with both 
Cambria and XITS, the brackets remain small.

Am I doing it wrong?

Will



\ifx\directlua\undefined
  \ifx\XeTeXversion\undefined\else
    \font\test="Cambria Math:script=math" at 10pt
    \textfont0=\test
  \fi
\else
  \input luaotfload.sty
  \font\test={name:Cambria Math:mode=base;script=math} at 10pt
  \textfont0=\test
\fi

\def\1{{\displaystyle x\over \displaystyle y}}
\def\2{{\displaystyle a\over \displaystyle b}}
\def\3{{\1\over\2}}

$$
\left( {x\over y} \right)
\left( \1\over\2 \right)
\left( \3\over\3 \right)
$$
$$
{x\overwithdelims() y}
{\1 \overwithdelims() \2}
{\3 \overwithdelims() \3}
$$

\bye