1 files changed, 65 insertions, 7 deletions

diff --git a/src/widgets/kernel/qwindowcontainer.cpp b/src/widgets/kernel/qwindowcontainer.cpp
index 847058e5b2..c15ec54f35 100644
--- a/src/widgets/kernel/qwindowcontainer.cpp
+++ b/src/widgets/kernel/qwindowcontainer.cpp
@@ -3,6 +3,7 @@
 
 #include "qwindowcontainer_p.h"
 #include "qwidget_p.h"
+#include "qwidgetwindow_p.h"
 #include <QtGui/qwindow.h>
 #include <QtGui/private/qguiapplication_p.h>
 #include <qpa/qplatformintegration.h>
@@ -14,6 +15,8 @@
 #include <QAbstractScrollArea>
 #include <QPainter>
 
+#include <QtCore/qpointer.h>
+
 QT_BEGIN_NAMESPACE
 
 using namespace Qt::StringLiterals;
@@ -162,11 +165,31 @@ public:
     application can greatly hurt the overall performance of the
     application.
 
+    \li Since 6.7, if \a window belongs to a widget (that is, \a window
+    was received from calling \l windowHandle()), no container will be
+    created. Instead, this function will return the widget itself, after
+    being reparented to \l parent. Since no container will be created,
+    \a flags will be ignored. In other words, if \a window belongs to
+    a widget, consider just reparenting that widget to \a parent instead
+    of using this function.
+
     \endlist
  */
 
 QWidget *QWidget::createWindowContainer(QWindow *window, QWidget *parent, Qt::WindowFlags flags)
 {
+    // Embedding a QWidget in a window container doesn't make sense,
+    // and has various issues in practice, so just return the widget
+    // itself.
+    if (auto *widgetWindow = qobject_cast<QWidgetWindow *>(window)) {
+        QWidget *widget = widgetWindow->widget();
+        if (flags != Qt::WindowFlags()) {
+            qWarning() << window << "refers to a widget:" << widget
+                       << "WindowFlags" << flags << "will be ignored.";
+        }
+        widget->setParent(parent);
+        return widget;
+    }
     return new QWindowContainer(window, parent, flags);
 }
 
@@ -191,11 +214,16 @@ QWindowContainer::QWindowContainer(QWindow *embeddedWindow, QWidget *parent, Qt:
     d->fakeParent.setObjectName(windowName + "ContainerFakeParent"_L1);
 
     d->window->setParent(&d->fakeParent);
+    d->window->parent()->installEventFilter(this);
     d->window->setFlag(Qt::SubWindow);
 
     setAcceptDrops(true);
 
-    connect(QGuiApplication::instance(), SIGNAL(focusWindowChanged(QWindow*)), this, SLOT(focusWindowChanged(QWindow*)));
+    connect(qGuiApp, &QGuiApplication::focusWindowChanged,
+            this, &QWindowContainer::focusWindowChanged);
+
+    connect(containedWindow(), &QWindow::minimumHeightChanged, this, &QWindowContainer::updateGeometry);
+    connect(containedWindow(), &QWindow::minimumWidthChanged, this, &QWindowContainer::updateGeometry);
 }
 
 QWindow *QWindowContainer::containedWindow() const
@@ -220,6 +248,9 @@ QWindowContainer::~QWindowContainer()
         d->window->destroy();
 
     delete d->window;
+
+    disconnect(qGuiApp, &QGuiApplication::focusWindowChanged,
+               this, &QWindowContainer::focusWindowChanged);
 }
 
 
@@ -243,6 +274,26 @@ void QWindowContainer::focusWindowChanged(QWindow *focusWindow)
     \internal
  */
 
+bool QWindowContainer::eventFilter(QObject *o, QEvent *e)
+{
+    Q_D(QWindowContainer);
+    if (!d->window)
+        return false;
+
+    if (e->type() == QEvent::ChildRemoved) {
+        QChildEvent *ce = static_cast<QChildEvent *>(e);
+        if (ce->child() == d->window) {
+            o->removeEventFilter(this);
+            d->window = nullptr;
+        }
+    }
+    return false;
+}
+
+/*!
+    \internal
+ */
+
 bool QWindowContainer::event(QEvent *e)
 {
     Q_D(QWindowContainer);
@@ -251,12 +302,6 @@ bool QWindowContainer::event(QEvent *e)
 
     QEvent::Type type = e->type();
     switch (type) {
-    case QEvent::ChildRemoved: {
-        QChildEvent *ce = static_cast<QChildEvent *>(e);
-        if (ce->child() == d->window)
-            d->window = nullptr;
-        break;
-    }
     // The only thing we are interested in is making sure our sizes stay
     // in sync, so do a catch-all case.
     case QEvent::Resize:
@@ -271,10 +316,13 @@ bool QWindowContainer::event(QEvent *e)
     case QEvent::Show:
         d->updateUsesNativeWidgets();
         if (d->isStillAnOrphan()) {
+            d->window->parent()->removeEventFilter(this);
             d->window->setParent(d->usesNativeWidgets
                                  ? windowHandle()
                                  : window()->windowHandle());
             d->fakeParent.destroy();
+            if (d->window->parent())
+                d->window->parent()->installEventFilter(this);
         }
         if (d->window->parent()) {
             d->markParentChain();
@@ -328,6 +376,11 @@ bool QWindowContainer::event(QEvent *e)
     return QWidget::event(e);
 }
 
+QSize QWindowContainer::minimumSizeHint() const
+{
+    return containedWindow() ? containedWindow()->minimumSize() : QSize(0, 0);
+}
+
 typedef void (*qwindowcontainer_traverse_callback)(QWidget *parent);
 static void qwindowcontainer_traverse(QWidget *parent, qwindowcontainer_traverse_callback callback)
 {
@@ -345,7 +398,10 @@ static void qwindowcontainer_traverse(QWidget *parent, qwindowcontainer_traverse
 void QWindowContainer::toplevelAboutToBeDestroyed(QWidget *parent)
 {
     if (QWindowContainerPrivate *d = QWindowContainerPrivate::get(parent)) {
+        if (d->window->parent())
+            d->window->parent()->removeEventFilter(parent);
         d->window->setParent(&d->fakeParent);
+        d->window->parent()->installEventFilter(parent);
     }
     qwindowcontainer_traverse(parent, toplevelAboutToBeDestroyed);
 }
@@ -363,7 +419,9 @@ void QWindowContainer::parentWasChanged(QWidget *parent)
                 tld->createTLSysExtra();
                 Q_ASSERT(toplevel->windowHandle());
             }
+            d->window->parent()->removeEventFilter(parent);
             d->window->setParent(toplevel->windowHandle());
+            toplevel->windowHandle()->installEventFilter(parent);
             d->fakeParent.destroy();
             d->updateGeometry();
         }