//With a few tests, it seems to work
//Event handling may be messed up though
class GrAccentsTextField extends TextField{
    private final static HashMap<String, String> accented = new HashMap<String, String>();
    private LinkedList<String> queue = new LinkedList<String>();
    private boolean prevCharIsAccent = false;

    static{
        accented.put("α", "ά");
        accented.put("ε", "έ");
        accented.put("η", "ή");
        accented.put("ι", "ί");
        accented.put("ο", "ό");
        accented.put("υ", "ύ");
        accented.put("ω", "ώ");
        accented.put("Α", "Ά");
        accented.put("Ε", "Έ");
        accented.put("Η", "Ή");
        accented.put("Ι", "Ί");
        accented.put("Ο", "Ό");
        accented.put("Υ", "Ύ");
        accented.put("Ω", "Ώ");
    }

    public GrAccentsTextField(){
        this.addEventFilter(KeyEvent.KEY_PRESSED, new EventHandler<KeyEvent>() {
            @Override
            public void handle(KeyEvent event) {
                final String typedChar = event.getText();
                if (prevCharIsAccent && accented.containsKey(typedChar)) {
                    queue.add(typedChar);
                } else {
                    queue.clear();
                }

                prevCharIsAccent = !prevCharIsAccent && event.getCode() == KeyCode.UNDEFINED;
                if(prevCharIsAccent){
                    queue.add(typedChar);
                }
            }
        });

        this.addEventFilter(KeyEvent.KEY_TYPED, new EventHandler<KeyEvent>() {
            @Override
            public void handle(KeyEvent event) {
                if(!queue.isEmpty() && queue.peek().equals(event.getCharacter())){
                    final String typedChar = queue.remove();
                    if(accented.containsKey(typedChar)){
                        Event.fireEvent(event.getTarget(), new KeyEvent(
                                event.getSource(),
                                event.getTarget(),
                                event.getEventType(),
                                accented.get(typedChar),
                                accented.get(typedChar),
                                event.getCode(),
                                event.isShiftDown(),
                                event.isControlDown(),
                                event.isAltDown(),
                                event.isMetaDown())
                        );
                    }
                    event.consume();
                }
            }
        });
    }
}