kivy: do not open invoices, requests dialogs if list is empty

gui/kivy/main_window.py

@@ -837,12 +837,22 @@ class ElectrumWindow(App):
 
     def invoices_dialog(self, screen):
         from .uix.dialogs.invoices import InvoicesDialog
+        if len(self.wallet.invoices.sorted_list()) == 0:
+            self.show_info(' '.join([
+                _('No saved invoices.'),
+                _('Signed invoices are saved automatically when you scan them.'),
+                _('You may also save unsigned requests or contact addresses using the save button.')
+            ]))
+            return
         popup = InvoicesDialog(self, screen, None)
         popup.update()
         popup.open()
 
     def requests_dialog(self, screen):
         from .uix.dialogs.requests import RequestsDialog
+        if len(self.wallet.get_sorted_requests(self.electrum_config)) == 0:
+            self.show_info(_('No saved requests.'))
+            return
         popup = RequestsDialog(self, screen, None)
         popup.update()
         popup.open()

gui/kivy/uix/screens.py

@@ -217,7 +217,6 @@ class SendScreen(CScreen):
         pr = make_unsigned_request(req).SerializeToString()
         pr = PaymentRequest(pr)
         self.app.wallet.invoices.add(pr)
-        self.app.update_tab('invoices')
         self.app.show_info(_("Invoice saved"))
         if pr.is_pr():
             self.screen.is_pr = True