code: public void showElement(CmsContainerPageElementPanel elementWidget) {
  
          int index = 0;
          for (index = 0; index < getGroupContainerWidget().getWidgetCount(); index++) {
              if (CmsDomUtil.hasClass(HIDDEN_ELEMENT_CLASS, getGroupContainerWidget().getWidget(index).getElement())) {
                  break;
              }
          }
          getGroupContainerWidget().insert(elementWidget, index);
          elementWidget.getInheritanceInfo().setVisible(true);
          elementWidget.removeStyleName(HIDDEN_ELEMENT_CLASS);
          updateButtonVisibility(elementWidget);
          getGroupContainerWidget().refreshHighlighting();
          List<Element> elements = CmsDomUtil.getElementsByClass(
              HIDDEN_ELEMENT_OVERLAY_CLASS,
              Tag.div,
              elementWidget.getElement());
          for (Element element : elements) {
              element.removeFromParent();
          }
          if (CmsDomUtil.getElementsByClass(
              HIDDEN_ELEMENT_OVERLAY_CLASS,
              Tag.div,
              getGroupContainerWidget().getElement()).isEmpty()) {
              // if no other hidden elements present disable toggle button
              m_showElementsButton.disable(Messages.get().key(Messages.GUI_INHERITANCECONTAINER_NO_HIDDEN_ELEMENTS_0));
          }
          m_changedInheritanceInfo = true;
      }
docs: Shows a formerly hidden element and sets the visibility info to true.<p>
  
  @param elementWidget the element widget