JLabelのアイコンとテキストのどちらにマウスカーソルがあるかを調査する

Icon icon = UIManager.getIcon("OptionPane.informationIcon");
JLabel label = new JLabel("OptionPane.informationIcon", icon, SwingConstants.LEADING) {
  private final Rectangle viewRect = new Rectangle();
  private final Rectangle iconRect = new Rectangle();
  private final Rectangle textRect = new Rectangle();

  @Override public String getToolTipText(MouseEvent e) {
    SwingUtilities.calculateInnerArea(this, viewRect);
    SwingUtilities.layoutCompoundLabel(
        this,
        this.getFontMetrics(this.getFont()),
        this.getText(),
        this.getIcon(),
        this.getVerticalAlignment(),
        this.getHorizontalAlignment(),
        this.getVerticalTextPosition(),
        this.getHorizontalTextPosition(),
        viewRect,
        iconRect,
        textRect,
        this.getIconTextGap());
    String tip = super.getToolTipText(e);
    if (tip == null) {
      return null;
    } else if (iconRect.contains(e.getPoint())) {
      return "Icon: " + tip;
    } else if (textRect.contains(e.getPoint())) {
      return "Text: " + tip;
    } else {
      return "Border: " + tip;
    }
  }
};
label.setOpaque(true);
label.setBackground(Color.GREEN);
label.setBorder(BorderFactory.createMatteBorder(20, 10, 50, 30, Color.RED));
label.setToolTipText("ToolTipText ToolTipText");