kivy: fix fork detection gui

gui/kivy/main_window.py

@@ -113,12 +113,12 @@ class ElectrumWindow(App):
         chains = self.network.get_blockchains()
         def cb(name):
             for index, b in self.network.blockchains.items():
-                if name == self.network.get_blockchain_name(b):
+                if name == b.get_name():
                     self.network.follow_chain(index)
-                    #self.block
         names = [self.network.blockchains[b].get_name() for b in chains]
-        if len(names) >1:
+        if len(names) > 1:
-            ChoiceDialog(_('Choose your chain'), names, '', cb).open()
+            cur_chain = self.network.blockchain().get_name()
+            ChoiceDialog(_('Choose your chain'), names, cur_chain, cb).open()
 
     use_rbf = BooleanProperty(False)
     def on_use_rbf(self, instance, x):

lib/network.py

@@ -558,6 +558,7 @@ class Network(util.DaemonThread):
             self.send_subscriptions()
             self.set_status('connected')
             self.notify('updated')
+            self.notify('interfaces')
 
     @with_interface_lock
     def close_interface(self, interface):