docs: public void startEditingGroupcontainer(
          final CmsGroupContainerElementPanel groupContainer,
          final boolean isElementGroup) {
  
          removeEditButtonsPositionTimer();
          I_CmsSimpleCallback<Boolean> callback = new I_CmsSimpleCallback<Boolean>() {
  
              public void execute(Boolean arg) {
  
                  if (arg.booleanValue()) {
                      if (isElementGroup) {
                          m_groupEditor = CmsGroupContainerEditor.openGroupcontainerEditor(
                              groupContainer,
                              CmsContainerpageController.this,
                              m_handler);
                      } else {
                          m_groupEditor = CmsInheritanceContainerEditor.openInheritanceContainerEditor(
                              groupContainer,
                              CmsContainerpageController.this,
                              m_handler);
                      }
                  } else {
                      CmsNotification.get().send(
                          Type.WARNING,
                          Messages.get().key(Messages.GUI_NOTIFICATION_UNABLE_TO_LOCK_0));
                  }
              }
          };
          if ((m_groupEditor == null) && (groupContainer.isNew())) {
              callback.execute(Boolean.TRUE);
          } else {
              lockContainerpage(callback);
          }
  
      }