quickwidget example: Avoid potential for crash on close

Widgets that had been broken out to separate top-level windows would
live on after the mainwindow was closed. Subsequent attempts to move
them back to the tab widget would crash, since the that would be
deleted by then. Fix by closing detached top-level windows on
mainwindow close.

Fixes: QTBUG-122790
Pick-to: 6.7 6.6 6.5
Change-Id: I0ae268c5e30b6563dc1556b3f79a83418cc3c703
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 5 insertions, 2 deletions

diff --git a/examples/quick/quickwidgets/quickwidget/main.cpp b/examples/quick/quickwidgets/quickwidget/main.cpp
index 584cecfb00..f8e0b78844 100644
--- a/examples/quick/quickwidgets/quickwidget/main.cpp
+++ b/examples/quick/quickwidgets/quickwidget/main.cpp
@@ -112,10 +112,12 @@ void MainWindow::createQuickWidgetsInTabs(QMdiArea *mdiArea)
             if (widget->parent()) {
                 widget->setAttribute(Qt::WA_DeleteOnClose, true);
                 widget->setParent(nullptr);
+                connect(this, &QObject::destroyed, widget, &QWidget::close);
                 widget->show();
                 btn->setText(msgFromTopLevel);
             } else {
                 widget->setAttribute(Qt::WA_DeleteOnClose, false);
+                disconnect(this, &QObject::destroyed, widget, &QWidget::close);
                 tabWidget->addTab(widget, widget->windowTitle());
                 btn->setText(msgToTopLevel);
             }
@@ -201,8 +203,9 @@ int main(int argc, char **argv)
 
     optMultipleSample = parser.isSet(multipleSampleOption);
 
-    MainWindow mainWindow;
-    mainWindow.show();
+    MainWindow *mainWindow = new MainWindow;
+    mainWindow->setAttribute(Qt::WA_DeleteOnClose, true);
+    mainWindow->show();
 
     return app.exec();
 }