diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index a92454547a..580e71ff22 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -10543,8 +10543,8 @@ void QWidget::setParent(QWidget *parent, Qt::WindowFlags f)
     });
 #endif
 
-    bool resized = testAttribute(Qt::WA_Resized);
-    bool wasCreated = testAttribute(Qt::WA_WState_Created);
+    const bool resized = testAttribute(Qt::WA_Resized);
+    const bool wasCreated = testAttribute(Qt::WA_WState_Created);
     QWidget *oldtlw = window();
 
     if (f & Qt::Window) // Frame geometry likely changes, refresh.
@@ -10553,7 +10553,7 @@ void QWidget::setParent(QWidget *parent, Qt::WindowFlags f)
     QWidget *desktopWidget = nullptr;
     if (parent && parent->windowType() == Qt::Desktop)
         desktopWidget = parent;
-    bool newParent = (parent != parentWidget()) || !wasCreated || desktopWidget;
+    bool newParent = (parent != parentWidget()) || desktopWidget;
 
     if (newParent && parent && !desktopWidget) {
         if (testAttribute(Qt::WA_NativeWindow) && !QCoreApplication::testAttribute(Qt::AA_DontCreateNativeWidgetSiblings))
@@ -10572,7 +10572,9 @@ void QWidget::setParent(QWidget *parent, Qt::WindowFlags f)
             QCoreApplication::sendEvent(this, &e);
         }
     }
-    if (newParent && isAncestorOf(focusWidget()))
+    // If we get parented into another window, children will be folded
+    // into the new parent's focus chain, so clear focus now.
+    if (newParent && isAncestorOf(focusWidget()) && !(f & Qt::Window))
         focusWidget()->clearFocus();
 
     d->setParent_sys(parent, f);
@@ -10619,7 +10621,7 @@ void QWidget::setParent(QWidget *parent, Qt::WindowFlags f)
     // event to handle recreation/rebinding of the GL context, hence the
     // (f & Qt::MSWindowsOwnDC) clause (which is set on QGLWidgets on all
     // platforms).
-    if (newParent
+    if (newParent || !wasCreated
 #if QT_CONFIG(opengles2)
         || (f & Qt::MSWindowsOwnDC)
 #endif
diff --git a/tests/auto/widgets/dialogs/qdialog/tst_qdialog.cpp b/tests/auto/widgets/dialogs/qdialog/tst_qdialog.cpp
index a509f1135a..e585835c3d 100644
--- a/tests/auto/widgets/dialogs/qdialog/tst_qdialog.cpp
+++ b/tests/auto/widgets/dialogs/qdialog/tst_qdialog.cpp
@@ -86,6 +86,7 @@ private slots:
     void virtualsOnClose();
     void deleteOnDone();
     void quitOnDone();
+    void focusWidgetAfterOpen();
 };
 
 // Testing get/set functions
@@ -738,5 +739,22 @@ void tst_QDialog::quitOnDone()
     QCOMPARE(quitSpy.count(), 1);
 }
 
+void tst_QDialog::focusWidgetAfterOpen()
+{
+    QDialog dialog;
+    dialog.setLayout(new QVBoxLayout);
+
+    QPushButton *pb1 = new QPushButton;
+    QPushButton *pb2 = new QPushButton;
+    dialog.layout()->addWidget(pb1);
+    dialog.layout()->addWidget(pb2);
+
+    pb2->setFocus();
+    QCOMPARE(dialog.focusWidget(), static_cast<QWidget *>(pb2));
+
+    dialog.open();
+    QCOMPARE(dialog.focusWidget(), static_cast<QWidget *>(pb2));
+}
+
 QTEST_MAIN(tst_QDialog)
 #include "tst_qdialog.moc"
diff --git a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
index 2d77e4af93..8acba6748c 100644
--- a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
+++ b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
@@ -431,6 +431,9 @@ private slots:
     void deleteWindowInCloseEvent();
     void quitOnClose();
 
+    void setParentChangesFocus_data();
+    void setParentChangesFocus();
+
 private:
     bool ensureScreenSize(int width, int height);
 
@@ -12188,5 +12191,74 @@ void tst_QWidget::quitOnClose()
     QCOMPARE(quitSpy.count(), 2);
 }
 
+void tst_QWidget::setParentChangesFocus_data()
+{
+    QTest::addColumn<Qt::WindowType>("initialType");
+    QTest::addColumn<bool>("initialParent");
+    QTest::addColumn<Qt::WindowType>("targetType");
+    QTest::addColumn<bool>("targetParent");
+    QTest::addColumn<bool>("reparentBeforeShow");
+    QTest::addColumn<QString>("focusWidget");
+
+    for (const bool before : {true, false}) {
+        const char *tag = before ? "before" : "after";
+        QTest::addRow("give dialog parent, %s", tag)
+            << Qt::Dialog << false << Qt::Dialog << true << before << "lineEdit";
+        QTest::addRow("make dialog parentless, %s", tag)
+            << Qt::Dialog << true << Qt::Dialog << false << before << "lineEdit";
+        QTest::addRow("dialog to sheet, %s", tag)
+            << Qt::Dialog << true << Qt::Sheet << true << before << "lineEdit";
+        QTest::addRow("window to widget, %s", tag)
+            << Qt::Window << true << Qt::Widget << true << before << "windowEdit";
+        QTest::addRow("widget to window, %s", tag)
+            << Qt::Widget << true << Qt::Window << true << before << "lineEdit";
+    }
+}
+
+void tst_QWidget::setParentChangesFocus()
+{
+    QFETCH(Qt::WindowType, initialType);
+    QFETCH(bool, initialParent);
+    QFETCH(Qt::WindowType, targetType);
+    QFETCH(bool, targetParent);
+    QFETCH(bool, reparentBeforeShow);
+    QFETCH(QString, focusWidget);
+
+    QWidget window;
+    window.setObjectName("window");
+    QLineEdit *windowEdit = new QLineEdit(&window);
+    windowEdit->setObjectName("windowEdit");
+    windowEdit->setFocus();
+
+    std::unique_ptr<QWidget> secondary(new QWidget(initialParent ? &window : nullptr, initialType));
+    secondary->setObjectName("secondary");
+    QLineEdit *lineEdit = new QLineEdit(secondary.get());
+    lineEdit->setObjectName("lineEdit");
+    QPushButton *pushButton = new QPushButton(secondary.get());
+    pushButton->setObjectName("pushButton");
+    lineEdit->setFocus();
+
+    window.show();
+    QVERIFY(QTest::qWaitForWindowActive(&window));
+
+    if (reparentBeforeShow) {
+        secondary->setParent(targetParent ? &window : nullptr, targetType);
+        // making a widget into a window doesn't set a focusWidget until shown
+        if (secondary->focusWidget())
+            QCOMPARE(secondary->focusWidget()->objectName(), focusWidget);
+    }
+    secondary->show();
+    QApplication::setActiveWindow(secondary.get());
+    QVERIFY(QTest::qWaitForWindowActive(secondary.get()));
+
+    if (!reparentBeforeShow) {
+        secondary->setParent(targetParent ? &window : nullptr, targetType);
+        secondary->show(); // reparenting hides, so show again
+        QApplication::setActiveWindow(secondary.get());
+        QVERIFY(QTest::qWaitForWindowActive(secondary.get()));
+    }
+    QCOMPARE(QApplication::focusWidget()->objectName(), focusWidget);
+}
+
 QTEST_MAIN(tst_QWidget)
 #include "tst_qwidget.moc"