From 58f8dd4f92e0e647ed530554d7edf3d1a901f552 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C5=82a=C5=BCej=20Szczygie=C5=82?= <spaz16@wp.pl>
Date: Fri, 15 Jan 2016 02:29:57 +0100
Subject: [PATCH] QtWidgets: Allow to cover up the window container by another
 widget

When the window container already has a window handle, allow embedded
windows to use this handle as a parent. This change will allow proper
window stacking and clipping.

Task-number: QTBUG-50477
Change-Id: I8d656ecb99e0c42ae7a7ac461e5e5b5d801f5493
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>
---
 src/widgets/kernel/qwindowcontainer.cpp        | 11 +++++++++--
 .../qwindowcontainer/tst_qwindowcontainer.cpp  | 18 ++++++++++++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/src/widgets/kernel/qwindowcontainer.cpp b/src/widgets/kernel/qwindowcontainer.cpp
index 3885431b05..e8c4a763ee 100644
--- a/src/widgets/kernel/qwindowcontainer.cpp
+++ b/src/widgets/kernel/qwindowcontainer.cpp
@@ -84,6 +84,11 @@ public:
         if (usesNativeWidgets || window->parent() == 0)
             return;
         Q_Q(QWindowContainer);
+        if (q->internalWinId()) {
+            // Allow use native widgets if the window container is already a native widget
+            usesNativeWidgets = true;
+            return;
+        }
         QWidget *p = q->parentWidget();
         while (p) {
             if (
@@ -147,8 +152,10 @@ public:
     as a child of a QAbstractScrollArea or QMdiArea, it will
     create a \l {Native Widgets vs Alien Widgets} {native window} for
     every widget in its parent chain to allow for proper stacking and
-    clipping in this use case. Applications with many native child
-    windows may suffer from performance issues.
+    clipping in this use case. Creating a native window for the window
+    container also allows for proper stacking and clipping. This must
+    be done before showing the window container. Applications with
+    many native child windows may suffer from performance issues.
 
     The window container has a number of known limitations:
 
diff --git a/tests/auto/widgets/kernel/qwindowcontainer/tst_qwindowcontainer.cpp b/tests/auto/widgets/kernel/qwindowcontainer/tst_qwindowcontainer.cpp
index dfc53c9164..94b3f9089f 100644
--- a/tests/auto/widgets/kernel/qwindowcontainer/tst_qwindowcontainer.cpp
+++ b/tests/auto/widgets/kernel/qwindowcontainer/tst_qwindowcontainer.cpp
@@ -81,6 +81,7 @@ private slots:
     void testActivation();
     void testAncestorChange();
     void testDockWidget();
+    void testNativeContainerParent();
     void cleanup();
 
 private:
@@ -330,6 +331,23 @@ void tst_QWindowContainer::testDockWidget()
     QTRY_COMPARE(window->parent(), mainWindow.window()->windowHandle());
 }
 
+void tst_QWindowContainer::testNativeContainerParent()
+{
+    QWidget root;
+    root.setWindowTitle(QTest::currentTestFunction());
+    root.setGeometry(m_availableGeometry.x() + 50, m_availableGeometry.y() + 50, 200, 200);
+
+    Window *window = new Window();
+    QWidget *container = QWidget::createWindowContainer(window, &root);
+    container->setAttribute(Qt::WA_NativeWindow);
+    container->setGeometry(50, 50, 150, 150);
+
+    root.show();
+
+    QVERIFY(QTest::qWaitForWindowExposed(window));
+    QTRY_COMPARE(window->parent(), container->windowHandle());
+}
+
 QTEST_MAIN(tst_QWindowContainer)
 
 #include "tst_qwindowcontainer.moc"