diff --git a/lcl/interfaces/qt/qtwidgets.pas b/lcl/interfaces/qt/qtwidgets.pas
index 889be628df..3f00082191 100644
--- a/lcl/interfaces/qt/qtwidgets.pas
+++ b/lcl/interfaces/qt/qtwidgets.pas
@@ -13040,7 +13040,7 @@ begin
               SlotMouse(Sender, Event);
               HandleCheckChangedEvent(MousePos, Item, Event);
               if not QListWidgetItem_isSelected(Item) then
-                QListWidget_setCurrentItem(QListWidgetH(Widget), Item, QItemSelectionModelSelect);
+                QListWidget_setCurrentItem(QListWidgetH(Widget), Item, QItemSelectionModelClearAndSelect);
               QEvent_ignore(Event);
               Result := True;
               exit;
@@ -13848,6 +13848,23 @@ function TQtCheckListBox.EventFilter(Sender: QObjectH; Event: QEventH
   ): Boolean; cdecl;
 begin
   Result := False;
+  if (QEvent_type(Event) = QEventKeyPress) and
+    (QtVersionMajor = 4) and (QtVersionMinor >= 8) and
+     ((QKeyEvent_key(QKeyEventH(Event)) = QtKey_Up) or
+     (QKeyEvent_key(QKeyEventH(Event)) = QtKey_Down)) then
+  begin
+    {issue #31697}
+    Result:=inherited EventFilter(Sender, Event);
+    if ItemCount > 0 then
+    begin
+      if (getSelCount = 0) then
+      begin
+        Selected[0] := True;
+        Result := True;
+      end;
+      inherited signalSelectionChanged();
+    end;
+  end else
   if (QEvent_type(Event) = QEventMouseButtonDblClick) then
     // issue #25089
   else
@@ -13905,7 +13922,10 @@ begin
             if Assigned(Item) and (currentItem <> Item) then
             begin
               // DebugLn('TQtCheckListBox forced item change');
-              Self.setCurrentItem(Item, True);
+              // Self.setCurrentItem(Item, True);
+              {issue #31697}
+              QListWidget_setCurrentItem(QListWidgetH(Widget), Item, QItemSelectionModelSelectCurrent);
+              inherited signalSelectionChanged();
             end;
           end;
         end;
@@ -13959,6 +13979,11 @@ begin
   Msg.Msg := LM_CHANGED;
   Msg.WParam := PtrInt(QListWidget_row(QListWidgetH(Widget), Item));
   DeliverMessage(Msg);
+  if (QtVersionMajor = 4) and (QtVersionMinor >= 8) then
+  begin
+    QListWidget_setCurrentItem(QListWidgetH(Widget), Item, QItemSelectionModelSelectCurrent);
+    inherited signalSelectionChanged();
+  end;
 end;
 
 function TQtCheckListBox.GetItemCheckState(AIndex: Integer): QtCheckState;
diff --git a/lcl/interfaces/qt/qtwscontrols.pp b/lcl/interfaces/qt/qtwscontrols.pp
index 7bd3cd0c54..8c949e9c84 100644
--- a/lcl/interfaces/qt/qtwscontrols.pp
+++ b/lcl/interfaces/qt/qtwscontrols.pp
@@ -632,7 +632,7 @@ begin
   if AWinControl.HandleObjectShouldBeVisible and
     (LowerCase(AWinControl.Font.Name) = 'default') then
   begin
-    if AWinControl.IsParentFont then
+    if AWinControl.IsParentFont and Assigned(AWinControl.Parent) then
       SetFont(AWinControl, AWinControl.Parent.Font) {DO NOT TOUCH THIS PLEASE !}
     else
       SetFont(AWinControl, AWinControl.Font); {DO NOT TOUCH THIS PLEASE !}
diff --git a/lcl/interfaces/qt5/qtwidgets.pas b/lcl/interfaces/qt5/qtwidgets.pas
index a238cf07f6..7e54b76491 100644
--- a/lcl/interfaces/qt5/qtwidgets.pas
+++ b/lcl/interfaces/qt5/qtwidgets.pas
@@ -13015,7 +13015,7 @@ begin
               SlotMouse(Sender, Event);
               HandleCheckChangedEvent(MousePos, Item, Event);
               if not QListWidgetItem_isSelected(Item) then
-                QListWidget_setCurrentItem(QListWidgetH(Widget), Item, QItemSelectionModelSelect);
+                QListWidget_setCurrentItem(QListWidgetH(Widget), Item, QItemSelectionModelClearAndSelect);
               QEvent_ignore(Event);
               Result := True;
               exit;
@@ -13824,6 +13824,22 @@ function TQtCheckListBox.EventFilter(Sender: QObjectH; Event: QEventH
   ): Boolean; cdecl;
 begin
   Result := False;
+  if (QEvent_type(Event) = QEventKeyPress) and
+     ((QKeyEvent_key(QKeyEventH(Event)) = QtKey_Up) or
+     (QKeyEvent_key(QKeyEventH(Event)) = QtKey_Down)) then
+  begin
+    {issue #31697}
+    Result:=inherited EventFilter(Sender, Event);
+    if ItemCount > 0 then
+    begin
+      if (getSelCount = 0) then
+      begin
+        Selected[0] := True;
+        Result := True;
+      end;
+      inherited signalSelectionChanged();
+    end;
+  end else
   if (QEvent_type(Event) = QEventMouseButtonDblClick) then
     // issue #25089
   else
@@ -13882,7 +13898,9 @@ begin
             if Assigned(Item) and (currentItem <> Item) then
             begin
               // DebugLn('TQtCheckListBox forced item change');
-              Self.setCurrentItem(Item, True);
+              {issue #31697}
+              QListWidget_setCurrentItem(QListWidgetH(Widget), Item, QItemSelectionModelSelectCurrent);
+              inherited signalSelectionChanged();
             end;
           end;
         end;
@@ -13936,6 +13954,8 @@ begin
   Msg.Msg := LM_CHANGED;
   Msg.WParam := PtrInt(QListWidget_row(QListWidgetH(Widget), Item));
   DeliverMessage(Msg);
+  QListWidget_setCurrentItem(QListWidgetH(Widget), Item, QItemSelectionModelSelectCurrent);
+  inherited signalSelectionChanged();
 end;
 
 function TQtCheckListBox.GetItemCheckState(AIndex: Integer): QtCheckState;
diff --git a/lcl/interfaces/qt5/qtwscontrols.pp b/lcl/interfaces/qt5/qtwscontrols.pp
index f9047cfa71..72f3cd07df 100644
--- a/lcl/interfaces/qt5/qtwscontrols.pp
+++ b/lcl/interfaces/qt5/qtwscontrols.pp
@@ -625,12 +625,17 @@ begin
     Exit;
 
   Widget := TQtWidget(AWinControl.Handle);
-
   Widget.BeginUpdate;
-  // issue #28437
-  if AWinControl.HandleObjectShouldBeVisible and not AWinControl.IsParentFont and
-    (AWinControl.Font.Name = 'default') then
-      SetFont(AWinControl, AWinControl.Font);
+  // issue #28437, #30966 - regression from r53365: when FontChanged() is called
+  // here handle is recreated inside LCL, so we are dead - SEGFAULT.
+  if AWinControl.HandleObjectShouldBeVisible and
+    (LowerCase(AWinControl.Font.Name) = 'default') then
+  begin
+    if AWinControl.IsParentFont and Assigned(AWinControl.Parent) then
+      SetFont(AWinControl, AWinControl.Parent.Font) {DO NOT TOUCH THIS PLEASE !}
+    else
+      SetFont(AWinControl, AWinControl.Font); {DO NOT TOUCH THIS PLEASE !}
+  end;
 
   Widget.setVisible(AWinControl.HandleObjectShouldBeVisible);
   Widget.EndUpdate;