[pdftex] problems with non-final sigma

[Tigran Aivazian]

Hello,

I emailed to the maintainer of Babel/Greek with this question a couple of 
months ago but, unfortunately, even he didn't know what the solution to 
the problem is, so I decided to ask here (but cc'd Apostolos in case he 
already found the solution by now).

In the past, there used to be separate characters for normal sigma (s) and 
the final sigma (c), so printing a final or non-final version was trivial.

However, recently (in the last few years or so) someone decided to
"improve" the situation and made this context-sensitive, i.e.  
automatically decide whether "s" is going to be normal or a final sigma.  
Well, ok, maybe it is useful (though I prefer a fixed plain version for
certainty sake) but now it seems to be impossible to produce a non-final
sigma where the context demands a final version.

An example of such situation is a table of the alphabet where a letter 
appears on its own and LaTeX decides it must be final.

So far, the only workaround (a horrible fontsize-specific one) I invented 
is to use "color" package and print another letter after it and then 
backspace and overprint it with white color, like this:

% a curious way to force non-final sigma:
% draw an alpha after sigma and then backspace and draw
% another alpha over it with white color.
% then backspace again for the space balance
\newcommand{\mysigma}{%
        \textgreek{sa%
                \hspace{-5.56pt}%
                \textcolor{white}{a}%
                \hspace{-4pt}%
        }
}

Can someone please suggest a proper solution, i.e. how to force 
\textgreek{s} on its own to produce a non-final sigma? Thank you.

Kind regards
Tigran