public void updateKeyboardUI() {
   if (Skin.VIETNAMESE_KEY.isEnabled()) {
     chkVietnamese.setText(" V ");
     chkVietnamese.setBackground(Color.yellow);
     chkVietnamese.setBorder(BorderFactory.createLineBorder(Color.red, 1));
   } else {
     chkVietnamese.setText(" E ");
     chkVietnamese.setBackground(Color.cyan);
     chkVietnamese.setBorder(BorderFactory.createLineBorder(Color.blue, 1));
   }
 }
 public void switchKeyboard() {
   if (Skin.VIETNAMESE_KEY.isEnabled()) Skin.VIETNAMESE_KEY.setEnabled(false);
   else Skin.VIETNAMESE_KEY.setEnabled(true);
   updateKeyboardUI();
 }