code: private void addSubComponents() {
          menuButton.setName("InternalFrameTitlePane.menuButton");
          iconButton.setName("InternalFrameTitlePane.iconifyButton");
          maxButton.setName("InternalFrameTitlePane.maximizeButton");
          closeButton.setName("InternalFrameTitlePane.closeButton");
  
          add(menuButton);
          add(iconButton);
          add(maxButton);
          add(closeButton);
      }
docs: Add the button subcomponents to the title pane.