kivy labels plugin: use Clock

gui/kivy/main_window.py

@@ -254,6 +254,9 @@ class ElectrumWindow(App):
         # show error
         self.show_error("Unable to decode QR data")
 
+    def update_history_tab(self):
+        Clock.schedule_once(lambda dt: self.update_tab('history'))
+
     def update_tab(self, name):
         s = getattr(self, name + '_screen', None)
         if s:

plugins/labels/kivy.py

@@ -10,5 +10,5 @@ class Plugin(LabelsPlugin):
 
     def on_pulled(self, wallet):
         self.print_error('on pulled')
-        self.window.update_tab('history')
+        self.window.update_history_tab()