<MenuItem mnemonicParsing="false" text="%btn_undo" fx:id="undoButton">
                  <accelerator>
                    <KeyCodeCombination alt="UP" code="Z" control="UP" meta="UP" shift="UP" shortcut="DOWN" />
                  </accelerator>
                </MenuItem>

I have the above xml in my fxml file. On Windows with azerty it works fine, on Mac OS X with an azerty keyboard I have to press the meta+w key instead of z. When I type something in a textfield in my app the keyboard layout is respected.