From b6d86ac539d4cf57ef19ebda437572f319347327 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Krier?= <ced@b2ck.com>
Date: Mon, 16 Mar 2009 09:43:33 +0100
Subject: [PATCH] Prevent to add empty on_write

---
 tryton/gui/window/view_form/screen/screen.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tryton/gui/window/view_form/screen/screen.py b/tryton/gui/window/view_form/screen/screen.py
index 8e31ce67ba..5a8eb1ef1e 100644
--- a/tryton/gui/window/view_form/screen/screen.py
+++ b/tryton/gui/window/view_form/screen/screen.py
@@ -385,7 +385,8 @@ class Screen(SignalEvent):
         return position
 
     def set_on_write(self, func_name):
-        self.models.on_write.add(func_name)
+        if func_name:
+            self.models.on_write.add(func_name)
 
     def cancel_current(self):
         if self.current_model: