private @NotNull MouseEvent convertMouseEvent(@NotNull MouseEvent e) {
      // create a new event, almost exactly the same, but in the header
      return new MouseEvent(e.getComponent(), e.getID(), e.getWhen(), e.getModifiers(), e.getX(), 0, e.getXOnScreen(), header.getY(),
                            e.getClickCount(), e.isPopupTrigger(), e.getButton());
    }
private @NotNull MouseEvent convertMouseEvent(@NotNull MouseEvent e)