As of today, ISBoxer's mouse broadcasting A) is fully functional in windowed mode again, and B) includes the fake mouse cursor again! Hooray!

A) ISBoxer 38.3.426.1 - check version and update via About window in Help menu
B) Inner Space build 5431 - check version by hovering cursor over IS icon in the system tray, update if needed just by restarting Inner Space (and let it patch up before launching anything)

FYI: I recently started playing EVE in order to get a better handle on this and other issues for EVE players. I'm in the dual-boxing.com channel and I also set up an ISBoxer channel (which you are all welcome to join whether you use ISBoxer or not). I'm a complete noob at EVE so I'm still in the noob corp, and I have no real long term goal for playing yet. I will of course be showing off screenshots and videos when I have something interesting to share