Skip WA_DontShowOnScreen widgets when checking whether application can quit

QApplication tries to close all windows on quit using closeAllWindows,
but closeAllWindows skips some windows, in particular any widget with
WA_DontShowOnScreen set.

QApplication then tries to verify that all windows have been closed,
and that logic should skip the same kind of windows as closeAllWindows
does.

We include WA_DontShowOnScreen so that widgets that are proxied via
QGraphicProxyWidget will not prevent the application from quitting.

There's still some divergence between closeAllWindows and the logic
in QApplication::event's quit handling, but aligning that requires
more work than this particular fix, and should probably also be
based on using the return value of tryCloseAllWindows() directly.

Change-Id: I2555eeee0cb04b8e736109fed57f37150efd1964
Fixes: QTBUG-81107
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index bf3cf090ba..f334cc58f9 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -1868,7 +1868,7 @@ bool QApplication::event(QEvent *e)
         closeAllWindows();
         for (auto *w : topLevelWidgets()) {
             if (w->isVisible() && !(w->windowType() == Qt::Desktop) && !(w->windowType() == Qt::Popup) &&
-                 (!(w->windowType() == Qt::Dialog) || !w->parentWidget())) {
+                 (!(w->windowType() == Qt::Dialog) || !w->parentWidget()) && !w->testAttribute(Qt::WA_DontShowOnScreen)) {
                 e->ignore();
                 return true;
             }