qt receive tab: better "Clear" behaviour

Previously, the selection would not get cleared, and if the user clicked
again on the already selected item, the click would get ignored
(request would not get populated).

electrum/gui/qt/main_window.py

@@ -1206,6 +1206,7 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
         self.receive_amount_e.setAmount(None)
         self.expires_label.hide()
         self.expires_combo.show()
+        self.request_list.clearSelection()
 
     def toggle_qr_window(self):
         from . import qrwindow

electrum/gui/qt/request_list.py

@@ -27,7 +27,7 @@ from enum import IntEnum
 
 from PyQt5.QtGui import QStandardItemModel, QStandardItem
 from PyQt5.QtWidgets import QMenu
-from PyQt5.QtCore import Qt, QItemSelectionModel
+from PyQt5.QtCore import Qt, QItemSelectionModel, QModelIndex
 
 from electrum.i18n import _
 from electrum.util import format_time, get_request_status
@@ -75,7 +75,9 @@ class RequestList(MyTreeView):
                 self.selectionModel().setCurrentIndex(item, QItemSelectionModel.SelectCurrent | QItemSelectionModel.Rows)
                 break
 
-    def item_changed(self, idx):
+    def item_changed(self, idx: QModelIndex):
+        if not idx.isValid():
+            return
         # TODO use siblingAtColumn when min Qt version is >=5.11
         item = self.model().itemFromIndex(idx.sibling(idx.row(), self.Columns.DATE))
         request_type = item.data(ROLE_REQUEST_TYPE)
@@ -91,6 +93,10 @@ class RequestList(MyTreeView):
             self.parent.receive_payreq_e.setText(req.get('URI'))
             self.parent.receive_address_e.setText(req['address'])
 
+    def clearSelection(self):
+        super().clearSelection()
+        self.selectionModel().clearCurrentIndex()
+
     def refresh_status(self):
         m = self.model()
         for r in range(m.rowCount()):