static int withLeftAndRightMargin_defaultWidth = 6;

static JPanel withLeftAndRightMargin(Component c) {
  ret withLeftAndRightMargin(withLeftAndRightMargin_defaultWidth, c);
}

static JPanel withLeftAndRightMargin(int w, Component c) {
  ret withLeftAndRightMargin(w, w, c);
}

static JPanel withLeftAndRightMargin(final int w1, final int w2, final Component c) {
  ret swing(func -> JPanel {
    JPanel p = marginPanel();
    p.setBorder(BorderFactory.createEmptyBorder(0, w1, 0, w2));
    p.add(c);
    ret p;
  });
}

Began life as a copy of #1007247