qt: ReceiveTab: fix flickering zeroconf message

The ReceiveTab gets updated regularly (e.g. when syncing headers).
Every time it updates we would first show the invoice and then the
zeroconf confirmation overlay. This caused the overly to appear
flickering when there are updates in higher frequency.

Also we need to keep state if the user has already confirmed the
zeroconf message for this request, otherwise the question
will re-appear each time the user clicked "Accept" and the
ReceiveTab updates again.

electrum/gui/qt/receive_tab.py

@@ -20,6 +20,7 @@ from .util import read_QIcon, WWLabel, MessageBoxMixin, MONOSPACE_FONT, get_icon
 
 if TYPE_CHECKING:
     from .main_window import ElectrumWindow
+    from electrum.wallet import Request
 
 
 class ReceiveTab(QWidget, MessageBoxMixin, Logger):
@@ -101,6 +102,9 @@ class ReceiveTab(QWidget, MessageBoxMixin, Logger):
         self.receive_zeroconf_button = QPushButton(_('Accept'))
         self.receive_zeroconf_button.clicked.connect(self.on_accept_zeroconf)
 
+        self.previous_request = None  # type: Optional['Request']
+        self.confirmed_zeroconf_for_this_request = False  # type: bool
+
         def on_receive_rebalance():
             if self.receive_rebalance_button.suggestion:
                 chan1, chan2, delta = self.receive_rebalance_button.suggestion
@@ -221,7 +225,7 @@ class ReceiveTab(QWidget, MessageBoxMixin, Logger):
 
     def update_receive_widgets(self):
         b = self.config.GUI_QT_RECEIVE_TAB_QR_VISIBLE
-        self.receive_widget.update_visibility(b)
+        self.receive_widget.update_visibility(b, bool(self.receive_help_text.text()))
 
     def update_current_request(self):
         if len(self.request_list.selectionModel().selectedRows(0)) > 1:
@@ -229,6 +233,9 @@ class ReceiveTab(QWidget, MessageBoxMixin, Logger):
         else:
             key = self.request_list.get_current_key()
         req = self.wallet.get_request(key) if key else None
+        if req != self.previous_request:
+            self.previous_request = req
+            self.confirmed_zeroconf_for_this_request = False
         if req is None:
             self.receive_e.setText('')
             self.addr = self.URI = self.lnaddr = ''
@@ -243,7 +250,7 @@ class ReceiveTab(QWidget, MessageBoxMixin, Logger):
         self.ln_help = help_texts.ln_help
         can_rebalance = help_texts.can_rebalance()
         can_swap = help_texts.can_swap()
-        can_zeroconf = help_texts.can_zeroconf()
+        can_zeroconf = help_texts.can_zeroconf() if not self.confirmed_zeroconf_for_this_request else False
         self.receive_rebalance_button.suggestion = help_texts.ln_rebalance_suggestion
         self.receive_swap_button.suggestion = help_texts.ln_swap_suggestion
         self.receive_rebalance_button.setVisible(can_rebalance)
@@ -253,25 +260,26 @@ class ReceiveTab(QWidget, MessageBoxMixin, Logger):
         self.receive_zeroconf_button.setVisible(can_zeroconf)
         self.receive_zeroconf_button.setEnabled(can_zeroconf)
         text, data, help_text, title = self.get_tab_data()
+        if self.confirmed_zeroconf_for_this_request and help_texts.can_zeroconf():
+            help_text = ''
+        # set help before receive_e so we don't flicker from qr to help
+        self.receive_help_text.setText(help_text)
         self.receive_e.setText(text)
         self.receive_qr.setData(data)
-        self.receive_help_text.setText(help_text)
         for w in [self.receive_e, self.receive_qr]:
             w.setEnabled(bool(text) and (not help_text or can_zeroconf))
             w.setToolTip(help_text)
         # macOS hack (similar to #4777)
         self.receive_e.repaint()
         # always show
-        if can_zeroconf:
-            # show the help message if zeroconf so user can first accept it and still sees the invoice
-            # after accepting
-            self.receive_widget.show_help()
         self.receive_widget.setVisible(True)
         self.toggle_qr_button.setEnabled(True)
         self.update_receive_qr_window()
 
     def on_accept_zeroconf(self):
         self.receive_zeroconf_button.setVisible(False)
+        self.confirmed_zeroconf_for_this_request = True
+        self.receive_help_text.setText('')
         self.update_receive_widgets()
 
     def get_tab_data(self):
@@ -386,8 +394,8 @@ class ReceiveWidget(QWidget):
 
         self.setLayout(vbox)
 
-    def update_visibility(self, is_qr):
-        if str(self.textedit.toPlainText()):
+    def update_visibility(self, is_qr: bool, show_help: bool):
+        if str(self.textedit.toPlainText()) and not show_help:
             self.help_widget.setVisible(False)
             self.textedit.setVisible(not is_qr)
             self.qr.setVisible(is_qr)