JTableのセルに複数のJButtonを配置する

class ButtonsPanel extends JPanel {
  public final List<JButton> buttons =
    Arrays.asList(new JButton("view"), new JButton("edit"));
  public ButtonsPanel() {
    super();
    setOpaque(true);
    for (JButton b: buttons) {
      b.setFocusable(false);
      b.setRolloverEnabled(false);
      add(b);
    }
  }
}

class ButtonsRenderer extends ButtonsPanel
                      implements TableCellRenderer {
  public ButtonsRenderer() {
    super();
    setName("Table.cellRenderer");
  }

  @Override public Component getTableCellRendererComponent(
      JTable table, Object value, boolean isSelected,
      boolean hasFocus, int row, int column) {
    Color bgc = isSelected ? table.getSelectionBackground()
                           : table.getBackground()
    setBackground(bgc);
    return this;
  }
}

class ButtonsEditor extends ButtonsPanel
                    implements TableCellEditor {
  public ButtonsEditor(final JTable table) {
    super();
    // ---->
    // DEBUG: view button click
    //   -> control key down + edit button(same cell) press
    //   -> remain selection color
    MouseListener ml = new MouseAdapter() {
      @Override public void mousePressed(MouseEvent e) {
        ButtonModel m = ((JButton) e.getSource()).getModel();
        if (m.isPressed() && table.isRowSelected(table.getEditingRow())
                          && e.isControlDown()) {
          setBackground(table.getBackground());
        }
      }
    };
    buttons.get(0).addMouseListener(ml);
    buttons.get(1).addMouseListener(ml);
    // <----

    buttons.get(0).addActionListener(new ActionListener() {
      @Override public void actionPerformed(ActionEvent e) {
        fireEditingStopped();
        JOptionPane.showMessageDialog(table, "Viewing");
      }
    });

    buttons.get(1).addActionListener(new ActionListener() {
      @Override public void actionPerformed(ActionEvent e) {
        int row = table.convertRowIndexToModel(table.getEditingRow());
        Object o = table.getModel().getValueAt(row, 0);
        fireEditingStopped();
        JOptionPane.showMessageDialog(table, "Editing: " + o);
      }
    });

    addMouseListener(new MouseAdapter() {
      @Override public void mousePressed(MouseEvent e) {
        fireEditingStopped();
      }
    });
  }

  @Override public Component getTableCellEditorComponent(JTable table,
        Object value, boolean isSelected, int row, int column) {
    this.setBackground(table.getSelectionBackground());
    return this;
  }

  @Override public Object getCellEditorValue() {
    return "";
  }

  // Copied from AbstractCellEditor
  // protected EventListenerList listenerList = new EventListenerList();
  transient protected ChangeEvent changeEvent = null;
  @Override public boolean isCellEditable(java.util.EventObject e) {
    return true;
  }
// ...