diff -r bcc07ff2362c -r d5df428640ff dialogs/BlockPreviewDialog.py
--- a/dialogs/BlockPreviewDialog.py	Thu Aug 17 14:27:06 2017 +0300
+++ b/dialogs/BlockPreviewDialog.py	Thu Aug 17 15:43:25 2017 +0300
@@ -215,8 +215,7 @@
         # or another graphic element
         elif ((self.DefaultElementName is None or
                self.DefaultElementName.upper() != uppercase_element_name) and
-              uppercase_element_name in self.Controller.\
-                    GetEditedElementVariables(self.TagName)):
+              uppercase_element_name in self.Controller.GetEditedElementVariables(self.TagName)):
             message_format = _("\"%s\" element for this pou already exists!")
 
         # If an error have been identify, show error message dialog