@Override
  public void setAdditionalComponent(@Nullable JComponent comp) {
    BorderLayout layout = (BorderLayout)myAdditionalComponent.getLayout();
    Component prev = layout.getLayoutComponent(myAdditionalComponent, BorderLayout.CENTER);
    if (prev == comp) return;
    if (prev != null) myAdditionalComponent.remove(prev);
    if (comp != null) myAdditionalComponent.add(comp, BorderLayout.CENTER);
    myAdditionalComponent.revalidate();
  }
@Override
  public void setAdditionalComponent(@Nullable JComponent comp)