QMenu::popup(): don't change the menu's screen if called from exec()

Since b3fc5e1ea3eb4fe838ac716aaca4efaa5de5a814,
topData()->initialScreenIndex has always been short-lived: it only
remembers the screen in case the widget parent is a QDesktopScreenWidget
(gotten from QDesktopWidget::screen()), only until the window is
created.  Then it is reset.  In the case of exec() we need to avoid
calling setScreen() twice, because that would set the screen once, then
forget which screen it was supposed to be on, then set the screen again
when exec() calls popup().  This is achieved by using the stored
eventLoop pointer to detect that popup() is being called from exec(),
and avoid calling setScreen() a second time in popup(), because exec()
already needed to call createWinId() before it created the event loop.

Amends 82da8306bc1313b85632eee0faf858239261a092

Task-number: QTBUG-76162
Change-Id: I70da517b9d530630e59d103cb2a1ce11c897b2c8
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Joni Poikelin <joni.poikelin@qt.io>
(cherry picked from commit 648dac1ceb40a346adf2081997f5c6166c3ad503)

1 files changed, 10 insertions, 7 deletions

diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
index 8dff2ffc34..d60a484094 100644
--- a/src/widgets/widgets/qmenu.cpp
+++ b/src/widgets/widgets/qmenu.cpp
@@ -2362,14 +2362,17 @@ void QMenu::popup(const QPoint &p, QAction *atAction)
     // However if the QMenu was constructed with a QDesktopScreenWidget as its parent,
     // then initialScreenIndex was set, so we should respect that for the lifetime of this menu.
     // Use d->popupScreen to remember, because initialScreenIndex will be reset after the first showing.
-    const int screenIndex = d->topData()->initialScreenIndex;
-    if (screenIndex >= 0)
-        d->popupScreen = screenIndex;
-    if (auto s = QGuiApplication::screens().value(d->popupScreen)) {
-        if (d->setScreen(s))
+    // However if eventLoop exists, then exec() already did this by calling createWinId(); so leave it alone. (QTBUG-76162)
+    if (!d->eventLoop) {
+        const int screenIndex = d->topData()->initialScreenIndex;
+        if (screenIndex >= 0)
+            d->popupScreen = screenIndex;
+        if (auto s = QGuiApplication::screens().value(d->popupScreen)) {
+            if (d->setScreen(s))
+                d->itemsDirty = true;
+        } else if (d->setScreenForPoint(p)) {
             d->itemsDirty = true;
-    } else if (d->setScreenForPoint(p)) {
-        d->itemsDirty = true;
+        }
     }
 
     const bool contextMenu = d->isContextMenu();