qml: network status improvements

create NetworkStatusIndicator component
add forks/chaintips and lagging property to qenetwork
add synchronizing and synchronizing progress properties to qewallet
Note: new wallet synchronizing is not picked up in UI yet, missing
an is_up_to_date event at the start still..

electrum/gui/qml/qenetwork.py

@@ -10,6 +10,7 @@ class QENetwork(QObject, QtEventListener):
     def __init__(self, network, parent=None):
         super().__init__(parent)
         self.network = network
+        self._height = network.get_local_height() # init here, update event can take a while
         self.register_callbacks()
 
     _logger = get_logger(__name__)
@@ -22,12 +23,16 @@ class QENetwork(QObject, QtEventListener):
     proxyChanged = pyqtSignal()
     statusChanged = pyqtSignal()
     feeHistogramUpdated = pyqtSignal()
+    chaintipsChanged = pyqtSignal()
+    isLaggingChanged = pyqtSignal()
 
     # shared signal for static properties
     dataChanged = pyqtSignal()
 
     _height = 0
     _status = ""
+    _chaintips = 1
+    _islagging = False
     _fee_histogram = []
 
     @event_listener
@@ -35,7 +40,7 @@ class QENetwork(QObject, QtEventListener):
         self.networkUpdated.emit()
 
     @event_listener
-    def on_event_blockchain_updated(self, *args):
+    def on_event_blockchain_updated(self):
         if self._height != self.network.get_local_height():
             self._height = self.network.get_local_height()
             self._logger.debug('new height: %d' % self._height)
@@ -57,6 +62,16 @@ class QENetwork(QObject, QtEventListener):
         if self._status != self.network.connection_status:
             self._status = self.network.connection_status
             self.statusChanged.emit()
+        chains = len(self.network.get_blockchains())
+        if chains != self._chaintips:
+            self._logger.debug('chain tips # changed: ' + chains)
+            self._chaintips = chains
+            self.chaintipsChanged.emit()
+        server_lag = self.network.get_local_height() - self.network.get_server_height()
+        if self._islagging ^ (server_lag > 1):
+            self._logger.debug('lagging changed: ' + (server_lag > 1))
+            self._islagging = server_lag > 1
+            self.isLaggingChanged.emit()
 
     @event_listener
     def on_event_fee_histogram(self, histogram):
@@ -68,7 +83,7 @@ class QENetwork(QObject, QtEventListener):
     def height(self):
         return self._height
 
-    @pyqtProperty('QString', notify=defaultServerChanged)
+    @pyqtProperty(str, notify=defaultServerChanged)
     def server(self):
         return str(self.network.get_parameters().server)
 
@@ -83,15 +98,23 @@ class QENetwork(QObject, QtEventListener):
         net_params = net_params._replace(server=server)
         self.network.run_from_another_thread(self.network.set_parameters(net_params))
 
-    @pyqtProperty('QString', notify=statusChanged)
+    @pyqtProperty(str, notify=statusChanged)
     def status(self):
         return self._status
 
+    @pyqtProperty(int, notify=chaintipsChanged)
+    def chaintips(self):
+        return self._chaintips
+
+    @pyqtProperty(bool, notify=isLaggingChanged)
+    def isLagging(self):
+        return self._islagging
+
     @pyqtProperty(bool, notify=dataChanged)
     def isTestNet(self):
         return constants.net.TESTNET
 
-    @pyqtProperty('QString', notify=dataChanged)
+    @pyqtProperty(str, notify=dataChanged)
     def networkName(self):
         return constants.net.__name__.replace('Bitcoin','')