diff --git a/gen/__init__.py b/gen/__init__.py
index 261daa8..8ef53ae 100644
--- a/gen/__init__.py
+++ b/gen/__init__.py
@@ -189,6 +189,15 @@ class Type:
             res = True
         return res
 
+    def isSortable(self, usage='search'):
+        '''Can fields of this type be used for sorting purposes (when sorting
+           search results (p_usage="search") or when sorting reference fields
+           (p_usage="ref")?'''
+        if usage == 'search': return self.indexed
+        elif usage == 'ref':
+            return self.type in ('Integer', 'Float', 'Boolean', 'Date') or \
+                   ((self.type == 'String') and (self.format == 0))
+
 class Integer(Type):
     def __init__(self, validator=None, multiplicity=(0,1), index=None,
                  default=None, optional=False, editDefault=False, show=True,
diff --git a/gen/plone25/mixins/__init__.py b/gen/plone25/mixins/__init__.py
index 82ece9c..3323f40 100644
--- a/gen/plone25/mixins/__init__.py
+++ b/gen/plone25/mixins/__init__.py
@@ -668,6 +668,13 @@ class AbstractMixin:
         reverse = rq.get('reverse') == 'True'
         self.appy().sort(fieldName, sortKey=sortKey, reverse=reverse)
 
+    def isRefSortable(self, fieldName):
+        '''Can p_fieldName, which is a field defined on self, be used as a sort
+           key in a reference field?'''
+        appyType = self.getAppyType(fieldName, asDict=False)
+        if not appyType: return True # Probably implicit field 'title'.
+        return appyType.isSortable(usage='ref')
+
     def getWorkflow(self, appy=True):
         '''Returns the Appy workflow instance that is relevant for this
            object. If p_appy is False, it returns the DC workflow.'''
diff --git a/gen/plone25/skin/macros.pt b/gen/plone25/skin/macros.pt
index 153c91d..7473154 100644
--- a/gen/plone25/skin/macros.pt
+++ b/gen/plone25/skin/macros.pt
@@ -857,7 +857,7 @@
          class="listing nosort" width="100%" cellpadding="0" cellspacing="0">
     <tal:comment replace="nothing">Every item in fieldDescr is a FieldDescr instance,
       excepted for workflow state (which is not a field): in this case it is simply the
-      string "workflowState".</tal:comment>
+      string "workflow_state".</tal:comment>
 
     <tal:comment replace="nothing">Headers, with filters and sort arrows</tal:comment>
     <tr>
diff --git a/gen/plone25/skin/ref.pt b/gen/plone25/skin/ref.pt
index 405195c..dc2f077 100644
--- a/gen/plone25/skin/ref.pt
+++ b/gen/plone25/skin/ref.pt
@@ -68,14 +68,12 @@
   ref field according to the field that corresponds to this column.
 </tal:comment>
 <metal:sortIcons define-macro="sortIcons"
-    tal:define="ajaxBaseCall python: navBaseCall.replace('**v**', '\'%s\',\'SortReference\', {\'sortKey\':\'%s\', \'reverse\':\'**v**\'}' % (startNumber, shownField))">
+    tal:define="ajaxBaseCall python: navBaseCall.replace('**v**', '\'%s\',\'SortReference\', {\'sortKey\':\'%s\', \'reverse\':\'**v**\'}' % (startNumber, shownField))" tal:condition="python: canWrite and objs[0].isRefSortable(shownField)">
   <img style="cursor:pointer"
        tal:attributes="src string:$portal_url/skyn/sortAsc.png;
-                       title python: tool.translate('sort_asc');
                        onClick python: ajaxBaseCall.replace('**v**', 'False')"/>
   <img style="cursor:pointer"
        tal:attributes="src string:$portal_url/skyn/sortDesc.png;
-                       title python: tool.translate('sort_desc');
                        onClick python: ajaxBaseCall.replace('**v**', 'True')"/>
 </metal:sortIcons>
 
@@ -122,9 +120,10 @@
                  flavour python:tool.getFlavour(contextObj);
                  linkedPortalType python:flavour.getPortalType(appyType['klass']);
                  addPermission python: '%s: Add %s' % (tool.getAppName(), linkedPortalType);
+                 canWrite python: not isBack and member.has_permission(contextObj.getField(fieldName).write_permission, contextObj);
                  multiplicity python:test(isBack, appyType['backd']['multiplicity'], appyType['multiplicity']);
                  maxReached python:(multiplicity[1] != None) and (len(objs) >= multiplicity[1]);
-                 showPlusIcon python:not isBack and appyType['add'] and not maxReached and member.has_permission(addPermission, folder);
+                 showPlusIcon python:not isBack and appyType['add'] and not maxReached and member.has_permission(addPermission, folder) and canWrite;
                  atMostOneRef python: (multiplicity[1] == 1) and (len(objs)&lt;=1);
                  label python: tool.translate(labelId);
                  description python: tool.translate(descrId);