This plugin is a porting to XFCE of 'GNOME Window Applet' (http://gnome-look.org/content/show.php?content=103732).
It's source code is heavily based on that apple.

So authors are:

Andrej Belcijan <andrejx@gmail.com>
    Author of the original 'GNOME Window Applet' (see link above for details).
    
Alessio Piccoli <alepic@geckoblu.net>
    Author of the porting to XFCE.
    
Cedric Leporcq <cedl38 at gmail dot com>
    Adding extra options.
