code: protected void onHoverIn(MouseOverEvent event) {
  
          if ((getParentMenu().getSelectedItem() != null)
              && (getParentMenu().getSelectedItem() != this)
              && getParentMenu().getSelectedItem().hasSubmenu()) {
  
              getParentMenu().getSelectedItem().getSubMenu().onClose();
              getParentMenu().getSelectedItem().deselectItem();
          }
          if (hasSubmenu()) {
              getSubMenu().openPopup(this);
          }
          selectItem();
      }
docs: Implements the hover over action for a item.<p>
  
  First closes all sub menus that are not required anymore.
  And then reopens the necessary sub menus and activates the selected item.<p>
  
  @param event the mouse over event