static <A extends JComponent> A setMargin(final int w, final int h, final A a) {
  if (a != null) swing {
    a.setBorder(BorderFactory.createEmptyBorder(h, w, h, w));
  }
  ret a;
}

static <A extends JComponent> A setMargin(int w, A a) {
  ret setMargin(w, w, a);
}