static JPanel textFieldAndButton(S defaultText, S buttonText, VF1<S> onEnter) {
  ret textFieldAndButton(jtextfield(defaultText), buttonText, onEnter);
}

static JPanel textFieldAndButton(JTextField tf, S buttonText, VF1<S> onEnter) {
  ret textFieldAndButton(tf, buttonText, vf1ToIVF1(onEnter));
}

static JPanel textFieldAndButton(JTextField tf, S buttonText, IVF1<S> onEnter) {
  Runnable r = r { callF(onEnter, getText(tf)) };
  ret centerAndEastWithMargin(onEnter(tf, r), jbutton(buttonText, r));
}