When checked, the live wallpaper will react to touch events as a normal app, instead of being limited to standard tap and secondary tap wallpaper commands. This means that it is possible to scroll and swipe over the lightning wallpaper, just as if it was a regular home screen. This can however produce border effects, especially if the wallpaper is being scrolled because the home screen scrolls. In that case the wallpaper will receive the swipe gestures too, and as a result it will be scrolled twice: because of the swipe gesture, and because of the home screen being scrolled. In order to avoid this kind of border effect, either disable wallpaper scrolling in the launcher, or set the desktop scrolling direction to None in Lightning.
Setting this option to on can possibly be useful if the home screen or the live wallpaper doesn't scroll, or if the live wallpaper contains scrollable panels.
Note: if this option is turned on, the wallpaper tap and secondary tap commands are ignored (otherwise a tap would be registered twice).