Fix menu size in multiscreen setups

During QMenuPrivate::popup() and QMenuBarPrivate::popupAction(),
QMenuPrivate::popupGeometry() is called from updateActionRects() with
screen = 0 several times (from sizeHint() and various event handlers
triggered), which causes it to return the primary screen geometry
always.

To fix this for the non-QGraphicsView case, use the screen of
the menu when it is visible or the screen stored in a newly introduced
popupScreen member variable, which is set from a few places
in QMenuPrivate::popup().

Fixes: QTBUG-118434
Pick-to: 6.7 6.6 6.5
Change-Id: I6b18593d313719d628b0856004197ac59f46c270
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 8 insertions, 4 deletions

diff --git a/src/widgets/widgets/qmenubar.cpp b/src/widgets/widgets/qmenubar.cpp
index 9c44f005ea..1ffe82835d 100644
--- a/src/widgets/widgets/qmenubar.cpp
+++ b/src/widgets/widgets/qmenubar.cpp
@@ -281,17 +281,21 @@ void QMenuBarPrivate::popupAction(QAction *action, bool activateFirst)
     if (action->isEnabled() && action->menu()->isEnabled()) {
         closePopupMode = 0;
         activeMenu = action->menu();
-        activeMenu->d_func()->causedPopup.widget = q;
-        activeMenu->d_func()->causedPopup.action = action;
+        auto *activeMenuPriv = activeMenu->d_func();
+        activeMenuPriv->causedPopup.widget = q;
+        activeMenuPriv->causedPopup.action = action;
 
         QRect adjustedActionRect = actionRect(action);
         QPoint pos(q->mapToGlobal(QPoint(adjustedActionRect.left(), adjustedActionRect.bottom() + 1)));
-        QSize popup_size = activeMenu->sizeHint();
         //we put the popup menu on the screen containing the bottom-center of the action rect
         QScreen *menubarScreen = q->window()->windowHandle()->screen();
-        QScreen *popupScreen = menubarScreen->virtualSiblingAt(pos + QPoint(adjustedActionRect.width() / 2, 0));
+        QPointer<QScreen> popupScreen = menubarScreen->virtualSiblingAt(pos + QPoint(adjustedActionRect.width() / 2, 0));
         if (!popupScreen)
             popupScreen = menubarScreen;
+        std::swap(popupScreen, activeMenuPriv->popupScreen);
+        const QSize popup_size = activeMenu->sizeHint();
+        std::swap(popupScreen, activeMenuPriv->popupScreen);
+
         QRect screenRect = popupScreen->geometry();
         pos = QPoint(qMax(pos.x(), screenRect.x()), qMax(pos.y(), screenRect.y()));
         const bool fitUp = (pos.y() - popup_size.height() >= screenRect.top());