@jk @boots They just act like two completely independent mouse cursors, so say you can operate two apps at one. There's still only one focus though, and mouseover/hover is broken in most apps I think, so the utility is limited. I actually think some Windows apps let you do this too, but it's just a few lines in the X config.
@boots i remember this being on by default on my Windows 95 laptop, which had some early type of LCD screen where it'd blur a lot. i never lost my cursor again!!! it was killer.
@jk (linux does not have this feature as far as i know disappointingly)