[Xy-pic] Bug in xyps-c.tex?

[Johann Bauer]

Hello,

I wonder if there is a little bug in xyps-c.tex. I had stumbled across a 
slight vertical misaligning in a formula. When I wanted to fix it, I 
noticed that it occurred only when both of the extensions dvips and 
color were loaded.

To make it short: In xy.tex, line 272 goes

\xydef@\xymath@{\hbox\bgroup \dimen@=\the\fontdimen22\textfont\tw@ 
\xyinside@}

while in xyps-c.tex, the corresponding definition in line 42 says

\xydef@\xyPSmath@{\hbox\bgroup\dimen@=.55ex \checkxyPScolor@ \xyinside@}


Shouldn't the ".55ex" be replaced by "\the\fontdimen22\textfont\tw@"?

Here is an example where the misplacement occurs:

------------------
\documentclass{article}
\usepackage[dvips,color]{xy}
\begin{document}
If the extensions color und dvips are both loaded, the middle minus sign 
is slightly mispositioned:

$-\kern-2pt\xy -<0pt,\fontdimen22\textfont2>*!{-}\endxy\kern-2pt-$
\end{document}
------------------

Luckily, I could fix this by myself, so I consider my problem as solved. 
But maybe someone competent can tell me whether my suggestion makes 
sense or there is some reason for the different length of .55ex.

Regards, Johann