Don't set Screen parent to True as it must be a Record instance

review1100002

tryton/gui/window/view_form/view/form_gtk/many2many.py

@@ -223,7 +223,7 @@ class Many2Many(WidgetInterface):
         if field is None:
             self.screen.new_group()
             self.screen.current_record = None
-            self.screen.parent = True
+            self.screen.parent = None
             self.screen.display()
             return False
         new_group = field.get_client(record)

tryton/gui/window/view_form/view/form_gtk/one2many.py

@@ -441,7 +441,7 @@ class One2Many(WidgetInterface):
         if field is None:
             self.screen.new_group()
             self.screen.current_record = None
-            self.screen.parent = True
+            self.screen.parent = None
             self.screen.display()
             return False
         new_group = field.get_client(record)