3 files changed, 6 insertions, 3 deletions
diff --git a/src/widgets/dialogs/qfontdialog.cpp b/src/widgets/dialogs/qfontdialog.cpp
index c373bcf1df..b62cd58db7 100644
--- a/src/widgets/dialogs/qfontdialog.cpp
+++ b/src/widgets/dialogs/qfontdialog.cpp
@@ -1036,7 +1036,9 @@ void QFontDialog::done(int result)
 
 bool QFontDialogPrivate::canBeNativeDialog() const
 {
-    Q_Q(const QFontDialog);
+    // Don't use Q_Q here! This function is called from ~QDialog,
+    // so Q_Q calling q_func() invokes undefined behavior (invalid cast in q_func()).
+    const QDialog * const q = static_cast<const QDialog*>(q_ptr);
     if (nativeDialogInUse)
         return true;
     if (QCoreApplication::testAttribute(Qt::AA_DontUseNativeDialogs)
diff --git a/src/widgets/graphicsview/qgraphicsscene.cpp b/src/widgets/graphicsview/qgraphicsscene.cpp
index b63686cd77..6a4f740b84 100644
--- a/src/widgets/graphicsview/qgraphicsscene.cpp
+++ b/src/widgets/graphicsview/qgraphicsscene.cpp
@@ -717,7 +717,7 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
             ++it;
     }
 
-    QGraphicsObject *dummy = static_cast<QGraphicsObject *>(item);
+    QGraphicsObject *dummy = item->toGraphicsObject();
     cachedTargetItems.removeOne(dummy);
     cachedItemGestures.remove(dummy);
     cachedAlreadyDeliveredGestures.remove(dummy);
@@ -996,7 +996,7 @@ void QGraphicsScenePrivate::ungrabMouse(QGraphicsItem *item, bool itemIsDying)
         // If the item is a popup, go via removePopup to ensure state
         // consistency and that it gets hidden correctly - beware that
         // removePopup() reenters this function to continue removing the grab.
-        removePopup((QGraphicsWidget *)item, itemIsDying);
+        removePopup(popupWidgets.constLast(), itemIsDying);
         return;
     }
 
diff --git a/src/widgets/kernel/qtooltip.cpp b/src/widgets/kernel/qtooltip.cpp
index c606ef6375..78929d8cd5 100644
--- a/src/widgets/kernel/qtooltip.cpp
+++ b/src/widgets/kernel/qtooltip.cpp
@@ -342,6 +342,7 @@ bool QTipLabel::eventFilter(QObject *o, QEvent *e)
     case QEvent::FocusIn:
     case QEvent::FocusOut:
 #endif
+    case QEvent::Close: // For QTBUG-55523 (QQC) specifically: Hide tooltip when windows are closed
     case QEvent::MouseButtonPress:
     case QEvent::MouseButtonRelease:
     case QEvent::MouseButtonDblClick: