[luatex] Subscript drop too large

[Henri Menke]

On 9/27/18 7:50 PM, Hans Hagen wrote:
> On 9/27/2018 7:23 AM, Henri Menke wrote:
>> Dear list,
>>
>> When using a Unicode math font, the subscript drop increases by a lot.
>> It does not seem to be font dependent, so it's likely an engine issue.
>> Is there any parameter which I could tweak?
> 
> all kind of math parameters .. like
> 
> $ \the\Umathsubshiftdrop\textstyle\quad {gt}_{gt} $
> $ \Umathsubshiftdrop\textstyle.2ex      {gt}_{gt} $

This partly answers the question, but it seems that there is something
wrong with subscripts after boxes, see MWE below.  With XeTeX it looks
okay and the drop is basically the same with and without a Unicode math
font, but with LuaTeX the drop after the box is much larger with a
Unicode math font whereas the drop after a regular atom is the same.

\ifdefined\directlua
  \input luaotfload.sty
\fi
\font\math="Latin Modern Math" at 10pt
$\hbox{gt}_{gt} gt_{gt}$
\textfont0=\math
$\hbox{gt}_{gt} gt_{gt}$
\bye

> 
> Hans
> 
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