[ui] Disable creation form feature of the relation widget

views/dataobject.py

@@ -80,6 +80,8 @@ class ContainedRelationFacetWidget(rwdg.RelationFacetWidget):
 class ContainedSearchForRelatedEntitiesView(rwdg.SearchForRelatedEntitiesView):
     __select__ = rwdg.SearchForRelatedEntitiesView.__select__ & match_form_params('container')
 
+    has_creation_form = False
+
     def linkable_rset(self):
         """Return rset of entities to be displayed as possible values for the
         edited relation. You may want to override this.