Windows QPA: Fix release button event type after moving windows

Check whether the mouse is inside the window and report
MouseButtonRelease or QEvent::NonClientAreaMouseButtonRelease,
respectively. The inside case is triggered by programmatically
starting a size move via QPlatformWindow::startSystemResize()
(QSizeGrip) and was overlooked in
7c3ecf85a770cd7fef01ece935f88d8894de09b2.

Complements 45894408913f62f6f25a302d8ed07af57ac7db5d,
7c3ecf85a770cd7fef01ece935f88d8894de09b2.

Change-Id: I8f714dc768a163878c2b4a075470bcee2dfbd802
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>
Reviewed-by: Andre de la Rocha <andre.rocha@qt.io>

1 files changed, 16 insertions, 9 deletions

diff --git a/src/plugins/platforms/windows/qwindowsmousehandler.cpp b/src/plugins/platforms/windows/qwindowsmousehandler.cpp
index bec935cd80..add01f65cc 100644
--- a/src/plugins/platforms/windows/qwindowsmousehandler.cpp
+++ b/src/plugins/platforms/windows/qwindowsmousehandler.cpp
@@ -180,24 +180,31 @@ Qt::MouseButtons QWindowsMouseHandler::queryMouseButtons()
 
 void QWindowsMouseHandler::handleExitSizeMove(QWindow *window)
 {
-    // When moving a window by dragging the title bar, no WM_NCLBUTTONUP is
-    // received after WM_NCLBUTTONDOWN, WM_NCMOUSEMOVE (due to internal
-    // mouse capture), which can leave the left mouse button 'pressed'
-    // in QGuiApplication's state. Intercept WM_EXITSIZEMOVE to sync the buttons.
+    // Windows can be moved/resized by:
+    // 1) User moving a window by dragging the title bar: Causes a sequence
+    //    of WM_NCLBUTTONDOWN, WM_NCMOUSEMOVE but no WM_NCLBUTTONUP,
+    //    leaving the left mouse button 'pressed'
+    // 2) User choosing Resize/Move from System menu and using mouse/cursor keys:
+    //    No mouse events are received
+    // 3) Programmatically via QSizeGrip calling QPlatformWindow::startSystemResize/Move():
+    //    Mouse is left in pressed state after press on size grip (inside window),
+    //    no further mouse events are received
+    // For cases 1,3, intercept WM_EXITSIZEMOVE to sync the buttons.
     const Qt::MouseButtons currentButtons = QWindowsMouseHandler::queryMouseButtons();
     const Qt::MouseButtons appButtons = QGuiApplication::mouseButtons();
     if (currentButtons == appButtons)
         return;
     const Qt::KeyboardModifiers keyboardModifiers = QWindowsKeyMapper::queryKeyboardModifiers();
     const QPoint globalPos = QWindowsCursor::mousePosition();
-    const QPoint localPos = window->handle()->mapFromGlobal(globalPos);
+    const QPlatformWindow *platWin = window->handle();
+    const QPoint localPos = platWin->mapFromGlobal(globalPos);
+    const QEvent::Type type = platWin->geometry().contains(globalPos)
+        ? 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,
-                                                     QEvent::NonClientAreaMouseButtonRelease,
-                                                     keyboardModifiers,
-                                                     Qt::MouseEventNotSynthesized);
+                                                     currentButtons, button, type,
+                                                     keyboardModifiers);
         }
     }
 }