code: private void maybeUpdateScrollbarPositions() {
  
          if (!isAttached()) {
              return;
          }
  
          if (m_scrollbar != null) {
              int vPos = getVerticalScrollPosition();
              if (m_scrollbar.getVerticalScrollPosition() != vPos) {
                  m_scrollbar.setVerticalScrollPosition(vPos);
              }
          }
      }
docs: Synchronize the scroll positions of the scrollbars with the actual scroll
  position of the content.