JavaFX registers mnemonics and accelerators at the scene level. I'm not sure how

shortcut

hooks into them, but I'm assuming everything is registered as an accelerator (JavaFX requires using ALT for mnemonics) that calls

button.fire()

. If that's the case, accelerators are stored in an

ObservableMap<KeyCombination, Runnable>

, so registering F12 again should overwrite the existing accelerator.