Windows: Send synthetic mouse release after move/resize using right API

The end of a move or resize might happen with the mouse still inside
the non-client area of the window, in which case we correctly resolved
the type to QEvent::NonClientAreaMouseButtonRelease, but we sent it
via QWindowSystemInterface::handleMouseEvent, which sets nonClientArea
of the event to false. This in turn resulted in QGuiApplication sending
a synthetic QEvent::MouseMove in case the position was out of sync,
instead of the correct QEvent::NonClientAreaMouseMove.

This should really be cleaned up on the QWSI level, as there is no
reason to have a dedicated API for handleFrameStrutMouseEvent, when
handleMouseEvent already takes an event type, but for now we fix the
immediate issue in the Windows platform plugin.

Change-Id: I8a831f5f19adb0625b29b50ebce9c0c6514e93f3
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>
(cherry picked from commit b4afba0c3450fd0c14ec7bada098c4e82ca310e7)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 7 insertions, 3 deletions

diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index ed47ef2108..720350aeca 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -1596,9 +1596,13 @@ void QWindowsContext::handleExitSizeMove(QWindow *window)
         ? QEvent::MouseButtonRelease : QEvent::NonClientAreaMouseButtonRelease;
     for (Qt::MouseButton button : {Qt::LeftButton, Qt::RightButton, Qt::MiddleButton}) {
         if (appButtons.testFlag(button) && !currentButtons.testFlag(button)) {
-            QWindowSystemInterface::handleMouseEvent(window, localPos, globalPos,
-                                                     currentButtons, button, type,
-                                                     keyboardModifiers);
+            if (type == QEvent::NonClientAreaMouseButtonRelease) {
+                QWindowSystemInterface::handleFrameStrutMouseEvent(window, localPos, globalPos,
+                    currentButtons, button, type, keyboardModifiers);
+            } else {
+                QWindowSystemInterface::handleMouseEvent(window, localPos, globalPos,
+                    currentButtons, button, type, keyboardModifiers);
+            }
         }
     }
     if (d->m_systemInfo & QWindowsContext::SI_SupportsPointer)