diff -r 1cee610aecce -r 3bca72c8574d src/pyams_portal/views.py
--- a/src/pyams_portal/views.py	Thu Jun 21 16:38:12 2018 +0200
+++ b/src/pyams_portal/views.py	Fri Jun 22 13:00:07 2018 +0200
@@ -17,7 +17,7 @@
 
 # import interfaces
 from pyams_portal.interfaces import IPortalContext, IPortalPage, IPortalTemplateConfiguration, \
-    IPortalPortletsConfiguration, IPortletRenderer, IPortlet
+    IPortalPortletsConfiguration, IPortletRenderer, IPortlet, PREVIEW_MODE
 from pyams_skin.layer import IPyAMSUserLayer
 from pyams_utils.interfaces import VIEW_SYSTEM_PERMISSION
 from pyams_workflow.interfaces import IWorkflowPublicationInfo
@@ -87,9 +87,6 @@
         super(PortalContextIndexPage, self).update()
 
 
-PREVIEW_MODE = 'PREVIEW_MODE'
-
-
 @pagelet_config(name='preview.html', context=IPortalContext, layer=IPyAMSUserLayer,
                 permission=VIEW_SYSTEM_PERMISSION)
 class PortalContextPreviewPage(PortalContextIndexPage):