[texhax] Before and After Display Hooks

[Uwe Lueck]

"Donald Arseneau" <asnd at triumf.ca> wrote 02.05.2011 02:41:21:
> \everydisplay{\aftergroup\the\aftergroup\aftereverydisplay
>  \the\beforeeverydisplay}

"Vafa Khalighi" <vafa018 at gmail.com>wrote 02.05.2011 02:57:54:
> Thanks but this produces
>
> *start* 1+2=3
> end
>
> rather than
>
> start
> 1+2=3
> end

The stars like

http://tug.org/pipermail/texhax/2011-May/017418.html

represent *italics* in the HTML version of the posting,
probably the default font in math. This is in perfect accordance
with the original specification

> \beforeeverydisplay and \aftereverydisplay works
> for every single display just like how \everydisplay works.

which, however, may be at some odds with the rest
of the orginal specification.

I wondered whether it suffices for the application
to redefine LaTeX's \[, \], \display, and \enddisplay
in order to add something *outside* the display
(right before/after the `$$' in \[, \]).

Cheers,

    Uwe.