diff --git a/lcl/interfaces/qt/qtwidgets.pas b/lcl/interfaces/qt/qtwidgets.pas
index b82731c826..475ca2fb46 100644
--- a/lcl/interfaces/qt/qtwidgets.pas
+++ b/lcl/interfaces/qt/qtwidgets.pas
@@ -5652,7 +5652,19 @@ end;
 
 function TQtTabWidget.EventFilter(Sender: QObjectH; Event: QEventH): Boolean;
   cdecl;
+var
+  w: QWidgetH;
+  ResizeEvent: QResizeEventH;
+  i: Integer;
+  NewSize: TSize;
+  OldSize: TSize;
 begin
+
+  Result := False;
+  QEvent_accept(Event);
+  if LCLObject = nil then
+    exit;
+
   BeginEventProcessing;
   if (Sender = TabBar) then
   begin
@@ -5671,6 +5683,28 @@ begin
     end;
   end else
   begin
+    {qt doesn't call resize for inactive pages, so LCL don't know
+     about changes on inactive pages, we must send resizeEvent to
+     all pages except for active one.This is fix for #13018}
+    if QEvent_type(Event) = QEventResize then
+    begin
+      w := QTabWidget_currentWidget(QTabWidgetH(Widget));
+      if w <> nil then
+      begin
+        QWidget_size(w, @NewSize);
+        OldSize.Cx := 0;
+        OldSize.Cy := 0;
+        for i := 0 to QTabWidget_count(QTabWidgetH(Widget)) - 1 do
+        begin
+          w := QTabWidget_widget(QTabWidgetH(Widget), i);
+          if w <> QTabWidget_currentWidget(QTabWidgetH(Widget)) then
+          begin
+            ResizeEvent := QResizeEvent_create(@NewSize, @OldSize);
+            QCoreApplication_postEvent(w, ResizeEvent, 1);
+          end;
+        end;
+      end;
+    end;
     Result := inherited EventFilter(Sender, Event);
   end;