Do not update counter label if widget has been removed

issue11110
review380011002
(grafted from 4ab42563da728f56273e9801b0a8e55df4840c72)

--HG--
branch : 6.0

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

@@ -193,7 +193,7 @@ class Link(StateMixin, Gtk.Button):
                         counter=counter, label=label))
 
     def _set_count(self, value, idx=0, current=None, counter=None, label=''):
-        if current != self._current:
+        if current != self._current and not self.get_parent():
             return
         try:
             counter[idx] = value()