diff -r ac0661486568 -r 7b3fa5a7a5a3 web/views/workflow.py
--- a/web/views/workflow.py	Thu Dec 12 16:17:25 2013 +0100
+++ b/web/views/workflow.py	Mon Jan 06 12:01:35 2014 +0100
@@ -29,6 +29,7 @@
 
 from logilab.mtconverter import xml_escape
 from logilab.common.graph import escape
+from logilab.common.deprecation import class_deprecated
 
 from cubicweb import Unauthorized
 from cubicweb.predicates import (has_related_entities, one_line_rset,
@@ -436,6 +437,8 @@
 
 
 class TmpPngView(TmpFileViewMixin, EntityView):
+    __metaclass__ = class_deprecated
+    __deprecation_warning__ = '[3.18] %(cls)s is deprecated'
     __regid__ = 'tmppng'
     __select__ = match_form_params('tmpfile')
     content_type = 'image/png'