return 1;
int delta;   if (orientation == SwingConstants.VERTICAL) {  int row = getClosestRowForLocation(visibleRect.x, visibleRect.y + 1); row = row + direction; if (row < 0) row = 0;  Rectangle newTop = getRowBounds(row); delta = newTop.y - visibleRect.y; } else delta = direction * rowHeight == 0 ? 20 : rowHeight; return delta;
  public int getScrollableUnitIncrement(Rectangle visibleRect,                                        int orientation, int direction)  {    return 1;  }