code: private static void installHoverbar(final CmsSitemapHoverbar hoverbar, CmsListItemWidget widget) {
  
          hoverbar.setVisible(false);
          widget.getContentPanel().add(hoverbar);
          A_CmsHoverHandler handler = new A_CmsHoverHandler() {
  
              /**
               * @see org.opencms.gwt.client.ui.A_CmsHoverHandler#onHoverIn(com.google.gwt.event.dom.client.MouseOverEvent)
               */
              @Override
              protected void onHoverIn(MouseOverEvent event) {
  
                  hoverbar.setHovered(true);
                  if (hoverbar.isVisible()) {
                      // prevent show when not needed
                      return;
                  }
                  hoverbar.show();
              }
  
              /**
               * @see org.opencms.gwt.client.ui.A_CmsHoverHandler#onHoverOut(com.google.gwt.event.dom.client.MouseOutEvent)
               */
              @Override
              protected void onHoverOut(MouseOutEvent event) {
  
                  hoverbar.setHovered(false);
                  if (!hoverbar.isLocked()) {
                      hoverbar.hide();
                  }
              }
          };
          widget.addMouseOutHandler(handler);
          widget.addMouseOverHandler(handler);
      }
docs: Installs the given hover bar.<p>
  
  @param hoverbar the hover bar
  @param widget the list item widget