QMenu: make wide submenu appear on the same screen with its parent menu

On a multi-display system wide submenu might either appear on wrong
screen or not appear at all (depending on the specific display
configuration).

Task-number: QTBUG-56917
Change-Id: I40013b0bee340a01ae1c08a5e074afa63da4dbfd
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@qt.io>
Reviewed-by: Błażej Szczygieł <spaz16@wp.pl>

2 files changed, 38 insertions, 2 deletions

diff --git a/src/widgets/widgets/qmenu.cpp b/src/widgets/widgets/qmenu.cpp
index 16f8734d7b..1925b58326 100644
--- a/src/widgets/widgets/qmenu.cpp
+++ b/src/widgets/widgets/qmenu.cpp
@@ -3501,11 +3501,22 @@ void QMenu::internalDelayedPopup()
     d->activeMenu->d_func()->causedPopup.widget = this;
     d->activeMenu->d_func()->causedPopup.action = d->currentAction;
 
+    QRect screen;
+#ifndef QT_NO_GRAPHICSVIEW
+    bool isEmbedded = !bypassGraphicsProxyWidget(this) && d->nearestGraphicsProxyWidget(this);
+    if (isEmbedded)
+        screen = d->popupGeometry(this);
+    else
+#endif
+    screen = d->popupGeometry(QApplication::desktop()->screenNumber(pos()));
+
     int subMenuOffset = style()->pixelMetric(QStyle::PM_SubMenuOverlap, 0, this);
     const QRect actionRect(d->actionRect(d->currentAction));
-    const QPoint rightPos(mapToGlobal(QPoint(actionRect.right() + subMenuOffset + 1, actionRect.top())));
+    QPoint subMenuPos(mapToGlobal(QPoint(actionRect.right() + subMenuOffset + 1, actionRect.top())));
+    if (subMenuPos.x() > screen.right())
+        subMenuPos.setX(QCursor::pos().x());
 
-    d->activeMenu->popup(rightPos);
+    d->activeMenu->popup(subMenuPos);
     d->sloppyState.setSubMenuPopup(actionRect, d->currentAction, d->activeMenu);
 
 #if !defined(Q_OS_DARWIN)
diff --git a/tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp b/tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp
index 4e82099706..b037cc2141 100644
--- a/tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp
+++ b/tests/auto/widgets/widgets/qmenu/tst_qmenu.cpp
@@ -113,6 +113,7 @@ private slots:
 #endif
     void QTBUG_56917_wideMenuSize();
     void QTBUG_56917_wideMenuScreenNumber();
+    void QTBUG_56917_wideSubmenuScreenNumber();
 protected slots:
     void onActivated(QAction*);
     void onHighlighted(QAction*);
@@ -1348,5 +1349,29 @@ void tst_QMenu::QTBUG_56917_wideMenuScreenNumber()
     }
 }
 
+void tst_QMenu::QTBUG_56917_wideSubmenuScreenNumber()
+{
+    if (QApplication::styleHints()->showIsFullScreen())
+        QSKIP("The platform defaults to windows being fullscreen.");
+    // submenu must appear on the same screen where its parent menu is shown
+    QString longString;
+    longString.fill(QLatin1Char('Q'), 3000);
+
+    for (int i = 0; i < QApplication::desktop()->screenCount(); i++) {
+        QMenu menu;
+        QMenu submenu("Submenu");
+        submenu.addAction(longString);
+        QAction *action = menu.addMenu(&submenu);
+        menu.popup(QApplication::desktop()->screen(i)->geometry().center());
+        QVERIFY(QTest::qWaitForWindowExposed(&menu));
+        QVERIFY(menu.isVisible());
+        QTest::mouseClick(&menu, Qt::LeftButton, 0, menu.actionGeometry(action).center());
+        QTest::qWait(100);
+        QVERIFY(QTest::qWaitForWindowExposed(&submenu));
+        QVERIFY(submenu.isVisible());
+        QCOMPARE(QApplication::desktop()->screenNumber(&submenu), i);
+    }
+}
+
 QTEST_MAIN(tst_QMenu)
 #include "tst_qmenu.moc"