Update attachment count when switching tabs for issue1317

(transplanted from dd5fc5447dc8351b228cbbec4b613d33cc1e3c19)

tryton/gui/main.py

@@ -1352,7 +1352,10 @@ class Main(object):
             if self.buttons[i]:
                 self.buttons[i].set_sensitive(
                         bool(view and (i in view.handlers)))
-        self.buttons['but_attach'].set_stock_id('tryton-attachment')
+        if hasattr(view, 'update_attachment_count'):
+            view.update_attachment_count()
+        else:
+            self._attachment_count(view, 0)
 
     def _attachment_count(self, widget, signal_data):
         label = _('Attachment(%d)') % signal_data

tryton/gui/window/form.py

@@ -222,13 +222,19 @@ class Form(SignalEvent):
         if obj_id >= 0:
             win = Attachment(self.model, obj_id, self.window)
             win.run()
-            value = self.screen.current_model
-            attachment_count = value.get_attachment_count(reload=True)
-            self.signal('attachment-count', attachment_count)
         else:
             self.message_info(_('No record selected!'))
+        self.update_attachment_count(reload=True)
         return True
 
+    def update_attachment_count(self, reload=False):
+        value = self.screen.current_model
+        if value:
+            attachment_count = value.get_attachment_count(reload=reload)
+        else:
+            attachment_count = 0
+        self.signal('attachment-count', attachment_count)
+
     def sig_switch(self, widget=None):
         if not self.modified_save():
             return