@Override
    protected void validateTree() {
      int height = myOldHeight;
      super.validateTree();
      height -= getHeight();

      if (height != 0 && !(myOldHeight == 0 && getComponentCount() > 0 && getPermanentHeaderComponent() == getComponent(0))) {
        myVerticalScrollBar.setValue(myVerticalScrollBar.getValue() - height);
      }
      myOldHeight = getHeight();
    }
@Override
    protected void validateTree()