Compress UpdateLater events

Handle UpdateLater events in QApplication::compressEvents

Change-Id: I0c63f88d8ed90fc56c093c534394461797d1336b
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit cb42c940787cf8c44e11f2b650d81c3d1eff1580)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/widgets/kernel/qapplication.cpp

@@ -792,6 +792,7 @@ bool QApplication::compressEvent(QEvent *event, QObject *receiver, QPostEventLis
     const QEvent::Type type = event->type();
     switch (type) {
     case QEvent::UpdateRequest:
+    case QEvent::UpdateLater:
     case QEvent::LayoutRequest:
     case QEvent::Resize:
     case QEvent::Move:
@@ -820,6 +821,10 @@ bool QApplication::compressEvent(QEvent *event, QObject *receiver, QPostEventLis
             static_cast<QMoveEvent *>(postedEvent.event)->m_pos =
                 static_cast<const QMoveEvent *>(event)->pos();
             break;
+        case QEvent::UpdateLater:
+            static_cast<QUpdateLaterEvent *>(postedEvent.event)->m_region +=
+                static_cast<const QUpdateLaterEvent *>(event)->region();
+            break;
         case QEvent::UpdateRequest:
         case QEvent::LanguageChange:
         case QEvent::LayoutRequest:

src/widgets/kernel/qwidget_p.h

@@ -82,6 +82,7 @@ public:
     inline const QRegion &region() const { return m_region; }
 
 protected:
+    friend class QApplication;
     QRegion m_region;
 };