highline.el and XEmacs

Hello, I use highline.el[1] to highlight alternative lines or
alternative N-lines.  Unfortunately under XEmacs there is a missing
feature: it can't highlight a line till the window border, only till the
last character of the line, as it is written inside the elisp file:

The .el file on my system
(/usr/share/xemacs21/xemacs-packages/lisp/edit-utils/highline.el.gz) says:

,----
| (defcustom highline-line nil
|   "*Specify which part of line should be highlighted.
|
| Valid values are:
|
|    t                  mark up to end of line.
|
|    nil                mark up to window border.  On XEmacs, it behaves as t.
|                       NOTE: Let me know, if you find a way to mark up to
|                             window border on XEmacs.
| (...)
`----

>From the code it seems to me that under GNU Emacs
  (move-overlay overlay foo (1+ (line-end-position))
makes this "till window border" stuff.

How can I make it work in XEmacs?

Footnotes:
[1]  http://www.cpqd.com.br/~vinicius/emacs/highline.el.gz

-- 
...sutongi tti olleh