JavaFX, shortcuts, mnemonics, how to avoid sound signals

Question

I have a question regarding JavaFX 2.2: every time a mnemonic key is pressed (e.g. Alt-A, Alt-B, etc.), JavaFX beeps (Windows system sound plays by default). It does not matter whether the mnemonics are valid or not for the current components of the scene. If mnemomic is valid (for example, for Button or Label), JavaFX performs the corresponding action (the button is pressed or Label changes focus), but also signals that the user has taken an invalid action. I can only observe this for Alt-Key, no matter if they are used as mnemonics or an accelerator, Ctrl-Key works fine. How to avoid beeps for Alt-Key?

Is it possible to avoid sound signals by real action?
Do I have to handle events in any special way to fully consume them?

Is it possible to disable the entire application or scene or scene?

Regards, Annie