//please include function withMargin.

static int showForm_defaultGap = 4;

static JPanel showFormTitled(fS title, fO... _parts) {

  ret swing(func -> JPanel {

    final new Var<JFrame> frame;

    JPanel panel = showForm_makePanel(frame, _parts);

    frame.set(handleEscapeKey(minFrameWidth(showPackedFrame(title, withMargin(panel)), 400)));

    ret panel;

  });

}

static JPanel showForm_makePanel(final Var<JFrame> frame, O... _parts) {

  new L<L> l;

  L parts = asList(_parts);

  Runnable submit = null;

  for (int i = 0; i < l(parts); i++) {

    final O o = parts.get(i), next = get(parts, i+1);

    if (o instanceof Component || o instanceof S || next instanceof Component) { // smartAdd accepts strings

      l.add(ll(o == null ? new JPanel : o, next));

      if (next instanceof JButton && submit == null)

        submit = r { ((JButton) next).doClick() };

      i++;

    } else if (isRunnable(o))

      l.add(ll(null, jbutton(showFormSubmitButtonName(), submit = r {

        O result = call(o);

        if (neq(Boolean.FALSE, result))

          disposeFrame(frame.get());

      })));

    else print("showForm: Unknown element type: " + getClassName(o));

  }

  JPanel panel = hvgrid((L) l, showForm_defaultGap);

  if (submit != null)

    for (JTextField textField : childrenOfType(panel, JTextField.class))

      onEnter(textField, submit);

  ret panel;

}