Ensure QWindow::setParent() creates parent hierarchy if needed

If the QWindow has been created and has a platform window, we need to
ensure that the windows in the parent hierarchy also are created before
we set a new parent on the platform window, otherwise the platform window
will think that it's a top level window.

Change-Id: Icb2c3cd5411cd1eb595e8673e144095feda31df9
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>

1 files changed, 6 insertions, 7 deletions

diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index ec2e3e7367..f55e7f0803 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -612,20 +612,19 @@ void QWindow::setParent(QWindow *parent)
     }
 
     QObject::setParent(parent);
+    d->parentWindow = parent;
+
     if (parent)
         d->disconnectFromScreen();
     else
         d->connectToScreen(newScreen);
 
     if (d->platformWindow) {
-        if (parent && parent->d_func()->platformWindow) {
-            d->platformWindow->setParent(parent->d_func()->platformWindow);
-        } else {
-            d->platformWindow->setParent(0);
-        }
-    }
+        if (parent)
+            parent->create();
 
-    d->parentWindow = parent;
+        d->platformWindow->setParent(parent ? parent->d_func()->platformWindow : 0);
+    }
 
     QGuiApplicationPrivate::updateBlockedStatus(this);
 }