qt main_window: fix visual artifact when opening (re invoice lists)

InvoiceList.update() calls hide_if_empty(), which calls setVisible().
setVisible(True) should not be called before the widget is properly parented and put into a layout,
as that results in a blank window flashing up (appearing and disappearing) briefly.

electrum/gui/qt/invoice_list.py

@@ -73,7 +73,6 @@ class InvoiceList(MyTreeView):
         self.setModel(self.proxy)
         self.setSortingEnabled(True)
         self.setSelectionMode(QAbstractItemView.ExtendedSelection)
-        self.update()
 
     def refresh_row(self, key, row):
         invoice = self.parent.wallet.invoices.get(key)

electrum/gui/qt/main_window.py

@@ -1264,6 +1264,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
         vbox.addWidget(self.receive_requests_label)
         vbox.addWidget(self.request_list)
         vbox.setStretchFactor(self.request_list, 1000)
+        self.request_list.update()  # after parented and put into a layout, can update without flickering
 
         return w
 
@@ -1553,6 +1554,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
         vbox.addWidget(self.invoice_list)
         vbox.setStretchFactor(self.invoice_list, 1000)
         w.searchable_list = self.invoice_list
+        self.invoice_list.update()  # after parented and put into a layout, can update without flickering
         run_hook('create_send_tab', grid)
         return w
 

electrum/gui/qt/request_list.py

@@ -74,7 +74,6 @@ class RequestList(MyTreeView):
         self.setSortingEnabled(True)
         self.selectionModel().currentRowChanged.connect(self.item_changed)
         self.setSelectionMode(QAbstractItemView.ExtendedSelection)
-        self.update()
 
     def select_key(self, key):
         for i in range(self.model().rowCount()):