Unconnect screen when destroying by calling super

tryton/gui/window/form.py

@@ -221,7 +221,6 @@ class Form(SignalEvent, TabContent):
         parent.present()
 
     def destroy(self):
-        self.screen.signal_unconnect(self)
         self.screen.destroy()
         self.screen = None
         self.widget = None

tryton/gui/window/view_form/screen/screen.py

@@ -277,6 +277,7 @@ class Screen(SignalEvent):
         self.group.destroy()
         for view in self.views:
             view.destroy()
+        super(Screen, self).destroy()
         self.parent = None
         self.__group = None
         self.__current_record = None

tryton/gui/window/wizard.py

@@ -125,7 +125,6 @@ class Wizard(object):
 
     def destroy(self):
         if self.screen:
-            self.screen.signal_unconnect(self)
             self.screen.destroy()
             del self.screen
         del self.widget