public void setContent(@Nullable JComponent c) {
    if (myContent != null) {
      myContentGutter.remove(myContent);
    }

    myContent = new MyWrapper(c);

    myContent.setOpaque(false);

    invalidateContentBorder();

    myContentGutter.add(myContent, BorderLayout.CENTER);

    updateBanner();

    myComponent.revalidate();
    myComponent.repaint();
  }
public void setContent(@Nullable JComponent c)