static int withTopMargin_defaultWidth = 6;

static JPanel withTopMargin(Component c) {
  ret withTopMargin(withTopMargin_defaultWidth, c);
}

static JPanel withTopMargin(final int w, final Component c) {
  ret swing(func -> JPanel {
    JPanel p = new JPanel(new BorderLayout);
    p.setBorder(BorderFactory.createEmptyBorder(w, 0, 0, 0));
    p.add(c);
    ret p;
  });
}

Began life as a copy of #1004959