The fn applet has been updated to work with OS X Mavericks 10.9+. OS X now has a different method for allowing an app like this to work, luckily the change is quite simple. When you first run v1.2.1 it should tell you that the app must be approved to allow an app to control your computer. In System Preferences/Security/Accessibility you can add apps manually if necessary.

fn v1.2.1 (for OS X 10.9+ 125KB .zip)

release notes
v1.2.1
-updated for OS X Mavericks 10.9
v1.2
-released!
-(Universal version) localized for all standard listed languages of OS X 10.6

[ andoru.labs | $ ]