I don't normally use the feature of rolling up ("shading") a window. However, sometimes I bump the scroll region on my touchpad accidentally when the mouse pointer is over a window's titlebar. It's just an annoyance for me, but at least once it has also happened to a friend I had lent the computer to, who had no idea what had just happened. So it would be nice if there were an option to disable this feature.
xfconf-query -c xfwm4 -p /general/mousewheel_rollup -s false
*** This bug has been marked as a duplicate of bug 6989 ***