Karabiner (was KeyRemap4MacBook) is an awesome utility for keyboard customization on OS X.
- You can re-map any key without any restriction.
- You can accelerate speed of the key repeat.
__SimultaneousKeyPresses__sends key events continuously even if all keys are released when using multiple keyboards at the same time and both keyboards are pressed.
- Some Java apps might be crash when AXNotifier is enabled. (Spine, SpineTrial)
- OS X 10.9 or later