A while back E17 used to have a cool "bug" in the edge flipping logic.
Edge flipping is used on computer desktops when your have virtual desktop systems. Virtual desktops are very popular in Linux and UNIX desktop systems. One feature for virtual desktops is edge flipping. When edge flipping is enabled and one moves the mouse to the edge of the screen the screen will flip to an adjacent desktop if on is available.
This is probably pretty confusing if you are a windows user.
Anyway, I added some configuration: