static JButton renameButton(JComponent c, S name) {
  JButton b = first(childrenOfType(c, JButton.class));
  if (b != null)
    b.setText(name);
  ret b;
}

static JButton renameButton(JComponent c, S oldName, S newName) {
  for (JButton b : childrenOfType(c, JButton.class))
    if (eq(b.getText(), oldName)) {
      b.setText(newName);
      ret b;
    }
  null;
}