Send leave to most recently entered window when modal dialog is shown.

If a modal dialog was shown as a response to button click, the button
retained its hover highlight, because it didn't get leave event.

Fixed by tracking the most recently entered window and sending a leave
to it when modal dialog is shown that blocks it.

Also modified tst_QGuiApplication::modalWindow() autotest to check
for enters and leaves.

Task-number: QTBUG-27644
Change-Id: I387647e18a762a39d523e3df31221b9583a39f9d
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>

src/gui/kernel/qguiapplication.cpp

@@ -105,6 +105,7 @@ QPointF QGuiApplicationPrivate::lastCursorPosition(0.0, 0.0);
 
 bool QGuiApplicationPrivate::tabletState = false;
 QWindow *QGuiApplicationPrivate::tabletPressTarget = 0;
+QWindow *QGuiApplicationPrivate::currentMouseWindow = 0;
 
 QPlatformIntegration *QGuiApplicationPrivate::platform_integration = 0;
 QPlatformTheme *QGuiApplicationPrivate::platform_theme = 0;
@@ -455,6 +456,19 @@ void QGuiApplicationPrivate::showModalWindow(QWindow *modal)
 {
     self->modalWindowList.prepend(modal);
 
+    // Send leave for currently entered window if it should be blocked
+    if (currentMouseWindow && (currentMouseWindow->windowType() & Qt::Popup) != Qt::Popup) {
+        bool shouldBeBlocked = self->isWindowBlocked(currentMouseWindow);
+        if (shouldBeBlocked) {
+            // Remove the new window from modalWindowList temporarily so leave can go through
+            self->modalWindowList.removeFirst();
+            QEvent e(QEvent::Leave);
+            QGuiApplication::sendEvent(currentMouseWindow, &e);
+            currentMouseWindow = 0;
+            self->modalWindowList.prepend(modal);
+        }
+    }
+
     QEvent e(QEvent::WindowBlocked);
     QWindowList windows = QGuiApplication::topLevelWindows();
     for (int i = 0; i < windows.count(); ++i) {
@@ -1410,6 +1424,8 @@ void QGuiApplicationPrivate::processEnterEvent(QWindowSystemInterfacePrivate::En
         return;
     }
 
+    currentMouseWindow = e->enter;
+
     QEvent event(QEvent::Enter);
     QCoreApplication::sendSpontaneousEvent(e->enter.data(), &event);
 }
@@ -1423,6 +1439,8 @@ void QGuiApplicationPrivate::processLeaveEvent(QWindowSystemInterfacePrivate::Le
         return;
     }
 
+    currentMouseWindow = 0;
+
     QEvent event(QEvent::Leave);
     QCoreApplication::sendSpontaneousEvent(e->leave.data(), &event);
 }

src/gui/kernel/qguiapplication_p.h

@@ -189,6 +189,7 @@ public:
     static QPointF lastCursorPosition;
     static bool tabletState;
     static QWindow *tabletPressTarget;
+    static QWindow *currentMouseWindow;
 
 #ifndef QT_NO_CLIPBOARD
     static QClipboard *qt_clipboard;

src/gui/kernel/qwindow.cpp

@@ -214,6 +214,8 @@ QWindow::~QWindow()
 {
     if (QGuiApplicationPrivate::focus_window == this)
         QGuiApplicationPrivate::focus_window = 0;
+    if (QGuiApplicationPrivate::currentMouseWindow == this)
+        QGuiApplicationPrivate::currentMouseWindow = 0;
     QGuiApplicationPrivate::window_list.removeAll(this);
     destroy();
 }
@@ -1445,6 +1447,8 @@ bool QWindow::close()
 
     if (QGuiApplicationPrivate::focus_window == this)
         QGuiApplicationPrivate::focus_window = 0;
+    if (QGuiApplicationPrivate::currentMouseWindow == this)
+        QGuiApplicationPrivate::currentMouseWindow = 0;
 
     QGuiApplicationPrivate::window_list.removeAll(this);
     destroy();

src/widgets/kernel/qwidgetwindow.cpp

@@ -234,6 +234,7 @@ void QWidgetWindow::handleEnterLeaveEvent(QEvent *event)
                 while (enterParent->parent())
                     enterParent = enterParent->parent();
                 if (thisParent == enterParent) {
+                    QGuiApplicationPrivate::currentMouseWindow = enterWindow;
                     enter = enterWindow->widget();
                     QWindowSystemInterfacePrivate::removeWindowSystemEvent(systemEvent);
                 }

tests/auto/gui/kernel/qguiapplication/tst_qguiapplication.cpp

@@ -336,12 +336,11 @@ class BlockableWindow : public QWindow
     Q_OBJECT
 public:
     int blocked;
+    int leaves;
+    int enters;
 
     inline BlockableWindow()
-        : QWindow()
+        : QWindow(), blocked(false), enters(0), leaves(0) {}
-    {
-        blocked = false;
-    }
 
     bool event(QEvent *e)
     {
@@ -352,11 +351,23 @@ public:
         case QEvent::WindowUnblocked:
             --blocked;
             break;
+        case QEvent::Leave:
+            leaves++;
+            break;
+        case QEvent::Enter:
+            enters++;
+            break;
         default:
             break;
         }
         return QWindow::event(e);
     }
+
+    void resetCounts()
+    {
+        leaves = 0;
+        enters = 0;
+    }
 };
 
 void tst_QGuiApplication::modalWindow()
@@ -391,6 +402,12 @@ void tst_QGuiApplication::modalWindow()
     QCOMPARE(windowModalWindow2->blocked, 0);
     QCOMPARE(applicationModalWindow1->blocked, 0);
 
+    // enter mouse in window1
+    QWindowSystemInterface::handleEnterEvent(window1);
+    QGuiApplication::processEvents();
+    QCOMPARE(window1->enters, 1);
+    QCOMPARE(window1->leaves, 0);
+
     // show applicationModalWindow1, everything is blocked
     applicationModalWindow1->show();
     QCOMPARE(app.modalWindow(), applicationModalWindow1);
@@ -400,6 +417,24 @@ void tst_QGuiApplication::modalWindow()
     QCOMPARE(windowModalWindow2->blocked, 1);
     QCOMPARE(applicationModalWindow1->blocked, 0);
 
+    // opening modal causes leave for previously entered window, but not others
+    QGuiApplication::processEvents();
+    QCOMPARE(window1->enters, 1);
+    QCOMPARE(window1->leaves, 1);
+    QCOMPARE(window2->enters, 0);
+    QCOMPARE(window2->leaves, 0);
+    QCOMPARE(applicationModalWindow1->enters, 0);
+    QCOMPARE(applicationModalWindow1->leaves, 0);
+    window1->resetCounts();
+
+    // Try entering/leaving blocked window2 - no events should reach it
+    QWindowSystemInterface::handleEnterEvent(window2);
+    QGuiApplication::processEvents();
+    QWindowSystemInterface::handleLeaveEvent(window2);
+    QGuiApplication::processEvents();
+    QCOMPARE(window2->enters, 0);
+    QCOMPARE(window2->leaves, 0);
+
     // everything is unblocked when applicationModalWindow1 is hidden
     applicationModalWindow1->hide();
     QCOMPARE(app.modalWindow(), static_cast<QWindow *>(0));
@@ -409,6 +444,12 @@ void tst_QGuiApplication::modalWindow()
     QCOMPARE(windowModalWindow2->blocked, 0);
     QCOMPARE(applicationModalWindow1->blocked, 0);
 
+    // Enter window2 - should not be blocked
+    QWindowSystemInterface::handleEnterEvent(window2);
+    QGuiApplication::processEvents();
+    QCOMPARE(window2->enters, 1);
+    QCOMPARE(window2->leaves, 0);
+
     // show the windowModalWindow1, only window1 is blocked
     windowModalWindow1->show();
     QCOMPARE(app.modalWindow(), windowModalWindow1);
@@ -418,6 +459,15 @@ void tst_QGuiApplication::modalWindow()
     QCOMPARE(windowModalWindow2->blocked, 0);
     QCOMPARE(applicationModalWindow1->blocked, 0);
 
+    // opening window modal window doesn't cause leave for unblocked window
+    QGuiApplication::processEvents();
+    QCOMPARE(window1->enters, 0);
+    QCOMPARE(window1->leaves, 0);
+    QCOMPARE(window2->enters, 1);
+    QCOMPARE(window2->leaves, 0);
+    QCOMPARE(windowModalWindow1->enters, 0);
+    QCOMPARE(windowModalWindow1->leaves, 0);
+
     // show the windowModalWindow2, windowModalWindow1 is blocked as well
     windowModalWindow2->show();
     QCOMPARE(app.modalWindow(), windowModalWindow2);
@@ -472,6 +522,17 @@ void tst_QGuiApplication::modalWindow()
     QCOMPARE(windowModalWindow2->blocked, 1);
     QCOMPARE(applicationModalWindow1->blocked, 0);
 
+    // window2 gets finally the leave
+    QGuiApplication::processEvents();
+    QCOMPARE(window1->enters, 0);
+    QCOMPARE(window1->leaves, 0);
+    QCOMPARE(window2->enters, 1);
+    QCOMPARE(window2->leaves, 1);
+    QCOMPARE(windowModalWindow1->enters, 0);
+    QCOMPARE(windowModalWindow1->leaves, 0);
+    QCOMPARE(applicationModalWindow1->enters, 0);
+    QCOMPARE(applicationModalWindow1->leaves, 0);
+
     // hide applicationModalWindow1, windowModalWindow1 and window1 are blocked
     applicationModalWindow1->hide();
     QCOMPARE(app.modalWindow(), windowModalWindow2);