when using the space character as accelerator for a JMenuItem, it is not rendered correctly (I guess a ' ' is rendered, but that's kind of hard to see ;-).
OS X applications like iTunes (in the controls menu) do render the word "Space", localized to the current locale.

This is how it fails:

action.putValue(Action.ACCELERATOR_KEY, KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0));
new JMenuItem(action);