kivy: don't load kv from sign_transaction thread

gui/kivy/main_window.py

@@ -681,6 +681,18 @@ class ElectrumWindow(App):
         d = TxDialog(self, tx)
         d.open()
 
+    def sign_tx(self, *args):
+        import threading
+        threading.Thread(target=self._sign_tx, args=args).start()
+
+    def _sign_tx(self, tx, password, on_success, on_failure):
+        try:
+            self.wallet.sign_transaction(tx, password)
+        except InvalidPassword:
+            Clock.schedule_once(lambda dt: on_failure(_("Invalid PIN")))
+            return
+        Clock.schedule_once(lambda dt: on_success(tx))
+
     def broadcast(self, tx):
         if self.network and self.network.is_connected():
             self.show_info(_('Sending'))

gui/kivy/uix/screens.py

@@ -3,7 +3,6 @@ from decimal import Decimal
 import re
 import datetime
 import traceback, sys
-import threading
 
 from kivy.app import App
 from kivy.cache import Cache
@@ -285,23 +284,19 @@ class SendScreen(CScreen):
         msg.append(_("Enter your PIN code to proceed"))
         self.app.protected('\n'.join(msg), self.send_tx, (tx,))
 
-    def send_tx(self, *args):
-        threading.Thread(target=self.send_tx_thread, args=args).start()
-
-    def send_tx_thread(self, tx, password):
-        # sign transaction
+    def send_tx(self, tx, password):
+        def on_success(tx):
+            if tx.is_complete():
+                self.app.broadcast(tx)
+            else:
+                self.app.tx_dialog(tx)
+        def on_failure(error):
+            self.app.show_error(error)
         if self.app.wallet.can_sign(tx):
             self.app.show_info("Signing...")
-        try:
-            self.app.wallet.sign_transaction(tx, password)
-        except InvalidPassword:
-            self.app.show_error(_("Invalid PIN"))
-            return
-        if not tx.is_complete():
+            self.app.sign_tx(tx, password, on_success, on_failure)
+        else:
             self.app.tx_dialog(tx)
-            return
-        # broadcast
-        self.app.broadcast(tx)
 
 
 class ReceiveScreen(CScreen):