public void setContentComponent(@Nullable JComponent content) {
    if (content == null && myContent != null) {
      myPanel.remove(myContent);
    }
    myContent = content;
    if (myContent != null) {
      myContent.setVisible(myOn);
      myPanel.add(myContent, BorderLayout.CENTER);
    }
  }
public void setContentComponent(@Nullable JComponent content)