diff --git a/gen/__init__.py b/gen/__init__.py
index 3871aa3..0025f26 100755
--- a/gen/__init__.py
+++ b/gen/__init__.py
@@ -581,6 +581,17 @@ class Permission:
 class ReadPermission(Permission): pass
 class WritePermission(Permission): pass
 
+class No:
+    '''When you write a workflow condition method and you want to return False
+       but you want to give to the user some explanations about why a transition
+       can't be triggered, do not return False, return an instance of No
+       instead. When creating such an instance, you can specify an error
+       message.'''
+    def __init__(self, msg):
+        self.msg = msg
+    def __nonzero__(self):
+        return False
+
 # ------------------------------------------------------------------------------
 class Selection:
     '''Instances of this class may be given as validator of a String, in order
diff --git a/gen/plone25/mixins/PodTemplateMixin.py b/gen/plone25/mixins/PodTemplateMixin.py
index 2a13ab3..0e09ebf 100644
--- a/gen/plone25/mixins/PodTemplateMixin.py
+++ b/gen/plone25/mixins/PodTemplateMixin.py
@@ -3,6 +3,8 @@ import os, os.path, time, unicodedata
 from appy.shared import mimeTypes
 from appy.gen.plone25.mixins import AbstractMixin
 from StringIO import StringIO
+import appy.pod
+from appy.pod.renderer import Renderer
 
 # ------------------------------------------------------------------------------
 class PodError(Exception): pass
@@ -81,8 +83,6 @@ class PodTemplateMixin(AbstractMixin):
         if appySelf.tool.openOfficePort:
             rendererParams['ooPort'] = appySelf.tool.openOfficePort
         # Launch the renderer
-        import appy.pod
-        from appy.pod.renderer import Renderer
         try:
             renderer = Renderer(**rendererParams)
             renderer.run()
diff --git a/shared/__init__.py b/shared/__init__.py
index 64ee52d..9824416 100755
--- a/shared/__init__.py
+++ b/shared/__init__.py
@@ -41,15 +41,17 @@ class UnicodeBuffer:
     '''With StringIO class, I have tons of encoding problems. So I define a
        similar class here, that uses an internal unicode buffer.'''
     def __init__(self):
-        self.buffer = u''
+        self.buffer = []
     def write(self, s):
         if s == None: return
         if isinstance(s, unicode):
-            self.buffer += s
+            self.buffer.append(s)
         elif isinstance(s, str):
-            self.buffer += s.decode('utf-8')
+            self.buffer.append(s.decode('utf-8'))
         else:
-            self.buffer += unicode(s)
+            self.buffer.append(unicode(s))
+    def getValue(self):
+        return u''.join(self.buffer)
 
 # ------------------------------------------------------------------------------
 class Dummy: pass
diff --git a/shared/xml_parser.py b/shared/xml_parser.py
index 8590106..33e33a4 100755
--- a/shared/xml_parser.py
+++ b/shared/xml_parser.py
@@ -503,7 +503,7 @@ class XmlMarshaller:
         self.marshallSpecificElements(instance, res)
         # Return the result
         res.write('</'); res.write(self.rootElementName); res.write('>')
-        res = res.buffer
+        res = res.getValue()
         if not self.dumpUnicode:
             res = res.encode('utf-8')
         return res