Recreate child windows when changing screens

When setting a new screen, the code calls QWindow::destroy(), which
recursively destroys all child windows. It then calls create() on the
top-level window, leaving child windows destroyed. This causes crashes
if you have embedded native widgets.

Task-number: QTBUG-40817
Change-Id: Iaace2589f48bbfd5faaf5ff95357ff43b310504a
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

2 files changed, 22 insertions, 13 deletions

diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index d6f9fad070..6724d68c95 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -367,12 +367,31 @@ void QWindowPrivate::setScreen(QScreen *newScreen, bool recreate)
         if (newScreen) {
             q->connect(screen, SIGNAL(destroyed(QObject*)), q, SLOT(screenDestroyed(QObject*)));
             if (shouldRecreate)
-                q->create();
+                create(true);
         }
         emit q->screenChanged(newScreen);
     }
 }
 
+void QWindowPrivate::create(bool recursive)
+{
+    Q_Q(QWindow);
+    if (!platformWindow) {
+        platformWindow = QGuiApplicationPrivate::platformIntegration()->createPlatformWindow(q);
+        QObjectList childObjects = q->children();
+        for (int i = 0; i < childObjects.size(); i ++) {
+            QObject *object = childObjects.at(i);
+            if (object->isWindowType()) {
+                QWindow *window = static_cast<QWindow *>(object);
+                if (recursive)
+                    window->d_func()->create(true);
+                if (window->d_func()->platformWindow)
+                    window->d_func()->platformWindow->setParent(platformWindow);
+            }
+        }
+    }
+}
+
 void QWindowPrivate::clearFocusObject()
 {
 }
@@ -490,18 +509,7 @@ bool QWindow::isVisible() const
 void QWindow::create()
 {
     Q_D(QWindow);
-    if (!d->platformWindow) {
-        d->platformWindow = QGuiApplicationPrivate::platformIntegration()->createPlatformWindow(this);
-        QObjectList childObjects = children();
-        for (int i = 0; i < childObjects.size(); i ++) {
-            QObject *object = childObjects.at(i);
-            if(object->isWindowType()) {
-                QWindow *window = static_cast<QWindow *>(object);
-                if (window->d_func()->platformWindow)
-                    window->d_func()->platformWindow->setParent(d->platformWindow);
-            }
-        }
-    }
+    d->create(false);
 }
 
 /*!
diff --git a/src/gui/kernel/qwindow_p.h b/src/gui/kernel/qwindow_p.h
index 4305edea51..51d78bb9cd 100644
--- a/src/gui/kernel/qwindow_p.h
+++ b/src/gui/kernel/qwindow_p.h
@@ -132,6 +132,7 @@ public:
     void _q_clearAlert();
 
     void setScreen(QScreen *newScreen, bool recreate);
+    void create(bool recursive);
 
     virtual void clearFocusObject();