[ESS] Use of up arrow and down arrow keys

[Stephen Eglen]

 >     StEgl> Also, does the text "xemacs-flag" occur in your
 >     StEgl> .emacs?
 > 
 > I think that's the crucial question :
 > 
 > John: You need to define  xemacs-flag somewhere, since your
 > functions rely on it .
 > 
 > BTW, a more usual name for such a variable is  
 > 'xemacsp' (defined in GNU emacs) or 
 > 'xemacs-p'  as defined here locally :
 > 
 > (defconst xemacs-p
 >   (not (null (save-match-data (string-match "XEmacs\\|Lucid" emacs-version)))))

Another way of testing for xemacs:

(defconst xemacs-p (featurep 'xemacs))