gridPane.setFocusTraversable(true);
keyCombinationNodes = new HashMap<KeyCombination, Node>();
for (Node node : root.lookupAll(".keyCombinationId")) {
keyCombinationNodes.put(KeyCombination.valueOf(node.getId().replace('_', '+')), node);
}
for (Node node : root.lookupAll(".inputTextButton")) {
if (node instanceof Labeled) {
char firstChar = ((Labeled) node).getText().charAt(0);
KeyCharacterCombination kc = new KeyCharacterCombination(String.valueOf(firstChar));
keyCombinationNodes.put(kc, node);
}