Better support for USB devices

Benefits of this rewrite include:

- support of disconnecting / reconnecting a device without having
  to close the wallet, even in a different USB socket
- support of multiple keepkey / trezor devices, both during wallet
  creation and general use
- wallet is watching-only dynamically according to whether the
  associated device is currently plugged in or not

gui/qt/installwizard.py

@@ -132,13 +132,6 @@ class InstallWizard(WindowModalDialog, MessageBoxMixin, WizardBase):
         the password or None for no password."""
         return self.pw_dialog(msg or MSG_ENTER_PASSWORD, PasswordDialog.PW_NEW)
 
-    def query_hardware(self, choices, action):
-        if action == 'create':
-            msg = _('Select the hardware wallet to create')
-        else:
-            msg = _('Select the hardware wallet to restore')
-        return self.choice(msg, choices)
-
     def choose_server(self, network):
         # Show network dialog if config does not exist
         if self.config.get('server') is None:
@@ -323,7 +316,7 @@ class InstallWizard(WindowModalDialog, MessageBoxMixin, WizardBase):
             self.config.set_key('auto_connect', True, True)
             network.auto_connect = True
 
-    def choice(self, msg, choices):
+    def query_choice(self, msg, choices):
         vbox = QVBoxLayout()
         self.set_layout(vbox)
         gb2 = QGroupBox(msg)
@@ -335,7 +328,7 @@ class InstallWizard(WindowModalDialog, MessageBoxMixin, WizardBase):
         group2 = QButtonGroup()
         for i,c in enumerate(choices):
             button = QRadioButton(gb2)
-            button.setText(c[1])
+            button.setText(c)
             vbox2.addWidget(button)
             group2.addButton(button)
             group2.setId(button, i)
@@ -347,8 +340,7 @@ class InstallWizard(WindowModalDialog, MessageBoxMixin, WizardBase):
         vbox.addLayout(Buttons(CancelButton(self), next_button))
         if not self.exec_():
             raise UserCancelled
-        wallet_type = choices[group2.checkedId()][0]
-        return wallet_type
+        return group2.checkedId()
 
     def query_multisig(self, action):
         vbox = QVBoxLayout()

gui/qt/main_window.py

@@ -152,6 +152,9 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         self.connect(self, QtCore.SIGNAL('payment_request_error'), self.payment_request_error)
         self.history_list.setFocus(True)
 
+        self.connect(self, QtCore.SIGNAL('watching_only_changed'),
+                     self.watching_only_changed)
+
         # network callbacks
         if self.network:
             self.connect(self, QtCore.SIGNAL('network'), self.on_network_qt)
@@ -280,7 +283,6 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         self.warn_if_watching_only()
 
     def watching_only_changed(self):
-        self.saved_wwo = self.wallet.is_watching_only()
         title = 'Electrum %s  -  %s' % (self.wallet.electrum_version,
                                         self.wallet.basename())
         if self.wallet.is_watching_only():
@@ -495,6 +497,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         self.connect(sender, QtCore.SIGNAL('timersignal'), self.timer_actions)
 
     def timer_actions(self):
+        # Note this runs in the GUI thread
         if self.need_update.is_set():
             self.need_update.clear()
             self.update_wallet()
@@ -504,8 +507,6 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         if self.require_fee_update:
             self.do_update_fee()
             self.require_fee_update = False
-        if self.saved_wwo != self.wallet.is_watching_only():
-            self.watching_only_changed()
         run_hook('timer_actions')
 
     def format_amount(self, x, is_diff=False, whitespaces=False):