Borderの右下にJComponentを配置

public JComponent makePanel(JComponent m, JComponent c) {
  int ir = 20; // inset.right
  int ch = c.getPreferredSize().height / 2;
  Border ib = BorderFactory.createEmptyBorder(0, 0, ch, 0);
  Border eb = BorderFactory.createEtchedBorder();
  Border bo = BorderFactory.createCompoundBorder(eb, ib);
  m.setBorder(BorderFactory.createCompoundBorder(ib, bo));

  SpringLayout layout = new SpringLayout();
  JLayeredPane p = new JLayeredPane();
  p.setLayout(layout);

  Spring x = layout.getConstraint(SpringLayout.WIDTH, p);
  Spring y = layout.getConstraint(SpringLayout.HEIGHT, p);
  Spring g = Spring.minus(Spring.constant(ir));

  SpringLayout.Constraints constraints = layout.getConstraints(c);
  constraints.setConstraint(SpringLayout.EAST,  Spring.sum(x, g));
  constraints.setConstraint(SpringLayout.SOUTH, y);
  p.setLayer(c, JLayeredPane.DEFAULT_LAYER+1);
  p.add(c);

  constraints = layout.getConstraints(m);
  constraints.setConstraint(SpringLayout.WEST,  Spring.constant(0));
  constraints.setConstraint(SpringLayout.NORTH, Spring.constant(0));
  constraints.setConstraint(SpringLayout.EAST,  x);
  constraints.setConstraint(SpringLayout.SOUTH, y);
  p.setLayer(m, JLayeredPane.DEFAULT_LAYER);
  p.add(m);

  return p;
}