docs: public boolean isContainerEditable(I_CmsDropContainer dragParent) {
  
          boolean isSubElement = dragParent instanceof CmsGroupContainerElementPanel;
          boolean isContainerEditable = dragParent.isEditable()
              && (isSubElement || !isDetailPage() || dragParent.isDetailView() || dragParent.isDetailOnly());
          return isContainerEditable;
      }