Fix crash when windowcontainer is used in a dockwidget

The dockwidget's toplevel window would be a parent of the container's
window when floating. When plugged back into the mainwindow the
dockwidget's window is destroyed and the container's window along
with it. Added a function toplevelAboutToBeDestroyed to unparent
the containers window before this happens so parentWasChanged will
work correctly.

Change-Id: I06679cfb3a8fa3834c0db0be5973c012b8277275
Reviewed-by: Ulf Hermann <ulf.hermann@digia.com>
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/widgets/kernel/qwindowcontainer_p.h b/src/widgets/kernel/qwindowcontainer_p.h
index e2446bef42..a21f9bd35a 100644
--- a/src/widgets/kernel/qwindowcontainer_p.h
+++ b/src/widgets/kernel/qwindowcontainer_p.h
@@ -57,6 +57,7 @@ public:
     explicit QWindowContainer(QWindow *embeddedWindow, QWidget *parent = 0, Qt::WindowFlags f = 0);
     ~QWindowContainer();
 
+    static void toplevelAboutToBeDestroyed(QWidget *parent);
     static void parentWasChanged(QWidget *parent);
     static void parentWasMoved(QWidget *parent);
     static void parentWasRaised(QWidget *parent);