probable not exactly how there made but heres what i found
Window (http://www.houseslasher.com/m/index.php/t406.html)
Plane (http://www.houseslasher.com/m/index.php/t404.html)
Except for a few minor differences, these scripts pretty much implement the functionality of the "hidden" classes.
yea i was trying to get an idea how to create a curser for a class im working on now will probable just use the class in the window 1