QXcbWindow::handleLeaveNotifyEvent(): Consume when leaving geometry

QXcbConnection::mousePressWindow() returns the XCB toplevel window,
which has consumed the window system's last mouse press. When the
function returns a valid pointer, QXcbWindow::handleLeaveNotifyEvent()
didn't propagate the leave event to QWSI::handleLeaveEvent(). Instead,
the leave event was ingored.

That behavior is correct, e.g. when a button on the main window is
pressed and the mouse hovers away from the button, with the mouse
button continuously being pressed. It is not correct, if the mouse
cursor leaves the main window.

=> Ignore the leave event only as long as the mouse cursor remains
within mousePressWindow()->geometry().
=> Deliver the leave event, when the mouse cursor leaves the window.

Fixes: QTBUG-119864
Pick-to: 6.6 6.5 6.2 5.15
Change-Id: I30a6ebedcd148285b9f17dfd87885ff67726b54c
Reviewed-by: Liang Qi <liang.qi@qt.io>
(cherry picked from commit ec24b36)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/plugins/platforms/xcb/qxcbwindow.cpp

@@ -1981,10 +1981,15 @@ static inline bool doCheckUnGrabAncestor(QXcbConnection *conn)
     return true;
 }
 
-static bool ignoreLeaveEvent(quint8 mode, quint8 detail, QXcbConnection *conn = nullptr)
+static bool windowContainsGlobalPoint(QXcbWindow *window, int x, int y)
+{
+    return window ? window->geometry().contains(window->mapFromGlobal(QPoint(x, y))) : false;
+}
+
+static bool ignoreLeaveEvent(quint8 mode, quint8 detail, QXcbConnection *conn)
 {
     return ((doCheckUnGrabAncestor(conn)
-             && mode == XCB_NOTIFY_MODE_GRAB && detail == XCB_NOTIFY_DETAIL_ANCESTOR)
+            && mode == XCB_NOTIFY_MODE_GRAB && detail == XCB_NOTIFY_DETAIL_ANCESTOR)
             || (mode == XCB_NOTIFY_MODE_UNGRAB && detail == XCB_NOTIFY_DETAIL_INFERIOR)
             || detail == XCB_NOTIFY_DETAIL_VIRTUAL
             || detail == XCB_NOTIFY_DETAIL_NONLINEAR_VIRTUAL);
@@ -2004,14 +2009,13 @@ void QXcbWindow::handleEnterNotifyEvent(int event_x, int event_y, int root_x, in
 {
     connection()->setTime(timestamp);
 
-    const QPoint global = QPoint(root_x, root_y);
-
     if (ignoreEnterEvent(mode, detail, connection()) || connection()->mousePressWindow())
         return;
 
     // Updates scroll valuators, as user might have done some scrolling outside our X client.
     connection()->xi2UpdateScrollingDevices();
 
+    const QPoint global = QPoint(root_x, root_y);
     const QPoint local(event_x, event_y);
     QWindowSystemInterface::handleEnterEvent(window(), local, global);
 }
@@ -2021,8 +2025,11 @@ void QXcbWindow::handleLeaveNotifyEvent(int root_x, int root_y,
 {
     connection()->setTime(timestamp);
 
-    if (ignoreLeaveEvent(mode, detail, connection()) || connection()->mousePressWindow())
+    QXcbWindow *mousePressWindow = connection()->mousePressWindow();
+    if (ignoreLeaveEvent(mode, detail, connection())
+        || (mousePressWindow && windowContainsGlobalPoint(mousePressWindow, root_x, root_y))) {
         return;
+    }
 
     // check if enter event is buffered
     auto event = connection()->eventQueue()->peek([](xcb_generic_event_t *event, int type) {
@@ -2040,6 +2047,8 @@ void QXcbWindow::handleLeaveNotifyEvent(int root_x, int root_y,
         QWindowSystemInterface::handleEnterLeaveEvent(enterWindow->window(), window(), local, global);
     } else {
         QWindowSystemInterface::handleLeaveEvent(window());
+        if (!windowContainsGlobalPoint(this, root_x, root_y))
+            connection()->setMousePressWindow(nullptr);
     }
 
     free(enter);