From c3c6647e7888b7dbe9d9d22fb77bf08104a3653c Mon Sep 17 00:00:00 2001
From: Sine Striker <trueful@163.com>
Date: 周一, 11 12月 2023 02:14:32 +0800
Subject: [PATCH] refactor

---
 src/core/contexts/win32windowcontext.cpp |  994 ++++++++++++++++++++++++++++++++++++----------------------
 1 files changed, 620 insertions(+), 374 deletions(-)

diff --git a/src/core/contexts/win32windowcontext.cpp b/src/core/contexts/win32windowcontext.cpp
index 4af7626..9cf1ecc 100644
--- a/src/core/contexts/win32windowcontext.cpp
+++ b/src/core/contexts/win32windowcontext.cpp
@@ -1,14 +1,10 @@
 #include "win32windowcontext_p.h"
-#include "qwkcoreglobal_p.h"
 
 #include <optional>
 
 #include <QtCore/QHash>
-#include <QtCore/QAbstractNativeEventFilter>
-#include <QtCore/QCoreApplication>
-#include <QtCore/QOperatingSystemVersion>
 #include <QtCore/QScopeGuard>
-#include <QtCore/QTimer>
+#include <QtGui/QGuiApplication>
 
 #include <QtCore/private/qsystemlibrary_p.h>
 #include <QtGui/private/qhighdpiscaling_p.h>
@@ -24,19 +20,31 @@
 
 #include <shellscalingapi.h>
 #include <dwmapi.h>
+#include <timeapi.h>
+#include <versionhelpers.h>
 
+#include "nativeeventfilter.h"
+
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
 Q_DECLARE_METATYPE(QMargins)
+#endif
 
 namespace QWK {
 
-    static constexpr const auto kAutoHideTaskBarThickness =
-        quint8{2}; // The thickness of an auto-hide taskbar in pixels.
+    // The thickness of an auto-hide taskbar in pixels.
+    static constexpr const auto kAutoHideTaskBarThickness = quint8{2};
 
-    using WndProcHash = QHash<HWND, Win32WindowContext *>; // hWnd -> context
+    // hWnd -> context
+    using WndProcHash = QHash<HWND, Win32WindowContext *>;
     Q_GLOBAL_STATIC(WndProcHash, g_wndProcHash)
 
-    static WNDPROC g_qtWindowProc = nullptr; // Original Qt window proc function
+    // Original Qt window proc function
+    static WNDPROC g_qtWindowProc = nullptr;
 
+    // ### FIXME FIXME FIXME
+    // ### FIXME: Tell the user to call in the documentation, instead of automatically
+    // calling it directly.
+    // ### FIXME FIXME FIXME
     static struct QWK_Hook {
         QWK_Hook() {
             qApp->setAttribute(Qt::AA_DontCreateNativeWidgetSiblings);
@@ -44,27 +52,54 @@
     } g_hook{};
 
     struct DynamicApis {
-        decltype(&::DwmFlush) pDwmFlush = nullptr;
-        decltype(&::DwmIsCompositionEnabled) pDwmIsCompositionEnabled = nullptr;
-        decltype(&::GetDpiForWindow) pGetDpiForWindow = nullptr;
-        decltype(&::GetSystemMetricsForDpi) pGetSystemMetricsForDpi = nullptr;
-        decltype(&::GetDpiForMonitor) pGetDpiForMonitor = nullptr;
+//        template <typename T>
+//        struct DefaultFunc;
+//
+//        template <typename Return, typename... Args>
+//        struct DefaultFunc<Return(QT_WIN_CALLBACK *)(Args...)> {
+//            static Return STDAPICALLTYPE func(Args...) {
+//                return Return{};
+//            }
+//        };
+//
+// #define DYNAMIC_API_DECLARE(NAME) decltype(&::NAME) p##NAME =
+// DefaultFunc<decltype(&::NAME)>::func
+#define DYNAMIC_API_DECLARE(NAME) decltype(&::NAME) p##NAME = nullptr
+
+        DYNAMIC_API_DECLARE(DwmFlush);
+        DYNAMIC_API_DECLARE(DwmIsCompositionEnabled);
+        DYNAMIC_API_DECLARE(DwmGetCompositionTimingInfo);
+        DYNAMIC_API_DECLARE(GetDpiForWindow);
+        DYNAMIC_API_DECLARE(GetSystemMetricsForDpi);
+        DYNAMIC_API_DECLARE(GetDpiForMonitor);
+        DYNAMIC_API_DECLARE(timeGetDevCaps);
+        DYNAMIC_API_DECLARE(timeBeginPeriod);
+        DYNAMIC_API_DECLARE(timeEndPeriod);
+
+#undef DYNAMIC_API_DECLARE
 
         DynamicApis() {
-            QSystemLibrary user32(QStringLiteral("user32.dll"));
-            pGetDpiForWindow =
-                reinterpret_cast<decltype(pGetDpiForWindow)>(user32.resolve("GetDpiForWindow"));
-            pGetSystemMetricsForDpi = reinterpret_cast<decltype(pGetSystemMetricsForDpi)>(
-                user32.resolve("GetSystemMetricsForDpi"));
+#define DYNAMIC_API_RESOLVE(DLL, NAME)                                                             \
+    p##NAME = reinterpret_cast<decltype(p##NAME)>(DLL.resolve(#NAME))
 
-            QSystemLibrary shcore(QStringLiteral("shcore.dll"));
-            pGetDpiForMonitor =
-                reinterpret_cast<decltype(pGetDpiForMonitor)>(shcore.resolve("GetDpiForMonitor"));
+            QSystemLibrary user32(QStringLiteral("user32"));
+            DYNAMIC_API_RESOLVE(user32, GetDpiForWindow);
+            DYNAMIC_API_RESOLVE(user32, GetSystemMetricsForDpi);
 
-            QSystemLibrary dwmapi(QStringLiteral("dwmapi.dll"));
-            pDwmFlush = reinterpret_cast<decltype(pDwmFlush)>(dwmapi.resolve("DwmFlush"));
-            pDwmIsCompositionEnabled = reinterpret_cast<decltype(pDwmIsCompositionEnabled)>(
-                dwmapi.resolve("DwmIsCompositionEnabled"));
+            QSystemLibrary shcore(QStringLiteral("shcore"));
+            DYNAMIC_API_RESOLVE(shcore, GetDpiForMonitor);
+
+            QSystemLibrary dwmapi(QStringLiteral("dwmapi"));
+            DYNAMIC_API_RESOLVE(dwmapi, DwmFlush);
+            DYNAMIC_API_RESOLVE(dwmapi, DwmIsCompositionEnabled);
+            DYNAMIC_API_RESOLVE(dwmapi, DwmGetCompositionTimingInfo);
+
+            QSystemLibrary winmm(QStringLiteral("winmm"));
+            DYNAMIC_API_RESOLVE(winmm, timeGetDevCaps);
+            DYNAMIC_API_RESOLVE(winmm, timeBeginPeriod);
+            DYNAMIC_API_RESOLVE(winmm, timeEndPeriod);
+
+#undef DYNAMIC_API_RESOLVE
         }
 
         ~DynamicApis() = default;
@@ -159,20 +194,23 @@
     }
 
     static inline bool isWin8OrGreater() {
-        static const bool result =
-            QOperatingSystemVersion::current() >= QOperatingSystemVersion::Windows8;
+        static const bool result = ::IsWindows8OrGreater();
         return result;
     }
 
     static inline bool isWin8Point1OrGreater() {
-        static const bool result =
-            QOperatingSystemVersion::current() >= QOperatingSystemVersion::Windows8_1;
+        static const bool result = ::IsWindows8Point1OrGreater();
         return result;
     }
 
     static inline bool isWin10OrGreater() {
-        static const bool result =
-            QOperatingSystemVersion::current() >= QOperatingSystemVersion::Windows10;
+        static const bool result = ::IsWindows10OrGreater();
+        return result;
+    }
+
+    static inline bool isWin11OrGreater() {
+        static const bool result = ::IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_WIN10),
+                                                               LOBYTE(_WIN32_WINNT_WIN10), 22000);
         return result;
     }
 
@@ -189,27 +227,19 @@
     }
 
     static inline void triggerFrameChange(HWND hwnd) {
-        Q_ASSERT(hwnd);
-        if (!hwnd) {
-            return;
-        }
         ::SetWindowPos(hwnd, nullptr, 0, 0, 0, 0,
                        SWP_NOACTIVATE | SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER | SWP_NOOWNERZORDER |
                            SWP_FRAMECHANGED);
     }
 
     static inline quint32 getDpiForWindow(HWND hwnd) {
-        Q_ASSERT(hwnd);
-        if (!hwnd) {
-            return 0;
-        }
         const DynamicApis &apis = DynamicApis::instance();
         if (apis.pGetDpiForWindow) {         // Win10
             return apis.pGetDpiForWindow(hwnd);
         } else if (apis.pGetDpiForMonitor) { // Win8.1
             HMONITOR monitor = ::MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);
-            UINT dpiX{USER_DEFAULT_SCREEN_DPI};
-            UINT dpiY{USER_DEFAULT_SCREEN_DPI};
+            UINT dpiX{0};
+            UINT dpiY{0};
             apis.pGetDpiForMonitor(monitor, MDT_EFFECTIVE_DPI, &dpiX, &dpiY);
             return dpiX;
         } else { // Win2K
@@ -222,10 +252,6 @@
     }
 
     static inline quint32 getResizeBorderThickness(HWND hwnd) {
-        Q_ASSERT(hwnd);
-        if (!hwnd) {
-            return 0;
-        }
         const DynamicApis &apis = DynamicApis::instance();
         if (apis.pGetSystemMetricsForDpi) {
             const quint32 dpi = getDpiForWindow(hwnd);
@@ -237,10 +263,6 @@
     }
 
     static inline quint32 getTitleBarHeight(HWND hwnd) {
-        Q_ASSERT(hwnd);
-        if (!hwnd) {
-            return 0;
-        }
         const auto captionHeight = [hwnd]() -> int {
             const DynamicApis &apis = DynamicApis::instance();
             if (apis.pGetSystemMetricsForDpi) {
@@ -254,18 +276,13 @@
     }
 
     static inline void updateInternalWindowFrameMargins(HWND hwnd, QWindow *window) {
-        Q_ASSERT(hwnd);
-        Q_ASSERT(window);
-        if (!hwnd || !window) {
-            return;
-        }
         const auto margins = [hwnd]() -> QMargins {
             const int titleBarHeight = getTitleBarHeight(hwnd);
             if (isWin10OrGreater()) {
-                return { 0, -titleBarHeight, 0, 0 };
+                return {0, -titleBarHeight, 0, 0};
             } else {
                 const int frameSize = getResizeBorderThickness(hwnd);
-                return { -frameSize, -titleBarHeight, -frameSize, -frameSize };
+                return {-frameSize, -titleBarHeight, -frameSize, -frameSize};
             }
         }();
         const QVariant marginsVar = QVariant::fromValue(margins);
@@ -273,21 +290,19 @@
 #if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
         if (QPlatformWindow *platformWindow = window->handle()) {
             if (const auto ni = QGuiApplication::platformNativeInterface()) {
-                ni->setWindowProperty(platformWindow, QStringLiteral("_q_windowsCustomMargins"), marginsVar);
+                ni->setWindowProperty(platformWindow, QStringLiteral("WindowsCustomMargins"),
+                                      marginsVar);
             }
         }
 #else
-        if (const auto platformWindow = dynamic_cast<QNativeInterface::Private::QWindowsWindow *>(window->handle())) {
+        if (const auto platformWindow =
+                dynamic_cast<QNativeInterface::Private::QWindowsWindow *>(window->handle())) {
             platformWindow->setCustomMargins(margins);
         }
 #endif
     }
 
-    static inline std::optional<MONITORINFOEXW> getMonitorForWindow(HWND hwnd) {
-        Q_ASSERT(hwnd);
-        if (!hwnd) {
-            return std::nullopt;
-        }
+    static inline MONITORINFOEXW getMonitorForWindow(HWND hwnd) {
         // Use "MONITOR_DEFAULTTONEAREST" here so that we can still get the correct
         // monitor even if the window is minimized.
         HMONITOR monitor = ::MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);
@@ -297,23 +312,24 @@
         return monitorInfo;
     };
 
-    static inline bool isFullScreen(HWND hwnd) {
-        Q_ASSERT(hwnd);
-        if (!hwnd) {
-            return false;
-        }
+    static inline void moveToDesktopCenter(HWND hwnd) {
+        const auto monitorInfo = getMonitorForWindow(hwnd);
         RECT windowRect{};
         ::GetWindowRect(hwnd, &windowRect);
-        const std::optional<MONITORINFOEXW> mi = getMonitorForWindow(hwnd);
+        const auto newX = (RECT_WIDTH(monitorInfo.rcMonitor) - RECT_WIDTH(windowRect)) / 2;
+        const auto newY = (RECT_HEIGHT(monitorInfo.rcMonitor) - RECT_HEIGHT(windowRect)) / 2;
+        ::SetWindowPos(hwnd, nullptr, newX, newY, 0, 0,
+                       SWP_NOACTIVATE | SWP_NOSIZE | SWP_NOZORDER | SWP_NOOWNERZORDER);
+    }
+
+    static inline bool isFullScreen(HWND hwnd) {
+        RECT windowRect{};
+        ::GetWindowRect(hwnd, &windowRect);
         // Compare to the full area of the screen, not the work area.
-        return (windowRect == mi.value_or(MONITORINFOEXW{}).rcMonitor);
+        return (windowRect == getMonitorForWindow(hwnd).rcMonitor);
     }
 
     static inline bool isWindowNoState(HWND hwnd) {
-        Q_ASSERT(hwnd);
-        if (!hwnd) {
-            return false;
-        }
 #if 0
         WINDOWPLACEMENT wp{};
         wp.length = sizeof(wp);
@@ -325,16 +341,116 @@
 #endif
     }
 
-    static inline QPoint fromNativeLocalPosition(const QWindow *window, const QPoint &point) {
-        Q_ASSERT(window);
-        if (!window) {
-            return point;
+    static inline void syncPaintEventWithDwm() {
+        // No need to sync with DWM if DWM composition is disabled.
+        if (!isDwmCompositionEnabled()) {
+            return;
         }
-#if 1
-        return QHighDpi::fromNativeLocalPosition(point, window);
-#else
-        return QPointF(QPointF(point) / window->devicePixelRatio()).toPoint();
-#endif
+        const DynamicApis &apis = DynamicApis::instance();
+        // Dirty hack to workaround the resize flicker caused by DWM.
+        LARGE_INTEGER freq{};
+        ::QueryPerformanceFrequency(&freq);
+        TIMECAPS tc{};
+        apis.ptimeGetDevCaps(&tc, sizeof(tc));
+        const UINT ms_granularity = tc.wPeriodMin;
+        apis.ptimeBeginPeriod(ms_granularity);
+        LARGE_INTEGER now0{};
+        ::QueryPerformanceCounter(&now0);
+        // ask DWM where the vertical blank falls
+        DWM_TIMING_INFO dti{};
+        dti.cbSize = sizeof(dti);
+        apis.pDwmGetCompositionTimingInfo(nullptr, &dti);
+        LARGE_INTEGER now1{};
+        ::QueryPerformanceCounter(&now1);
+        // - DWM told us about SOME vertical blank
+        //   - past or future, possibly many frames away
+        // - convert that into the NEXT vertical blank
+        const auto period = qreal(dti.qpcRefreshPeriod);
+        const auto dt = qreal(dti.qpcVBlank - now1.QuadPart);
+        const qreal ratio = (dt / period);
+        auto w = qreal(0);
+        auto m = qreal(0);
+        if ((dt > qreal(0)) || qFuzzyIsNull(dt)) {
+            w = ratio;
+        } else {
+            // reach back to previous period
+            // - so m represents consistent position within phase
+            w = (ratio - qreal(1));
+        }
+        m = (dt - (period * w));
+        if ((m < qreal(0)) || qFuzzyCompare(m, period) || (m > period)) {
+            return;
+        }
+        const qreal m_ms = (qreal(1000) * m / qreal(freq.QuadPart));
+        ::Sleep(static_cast<DWORD>(std::round(m_ms)));
+        apis.ptimeEndPeriod(ms_granularity);
+    }
+
+    static inline void showSystemMenu2(HWND hWnd, const POINT &pos, const bool selectFirstEntry,
+                                       const bool fixedSize) {
+        const HMENU hMenu = ::GetSystemMenu(hWnd, FALSE);
+        if (!hMenu) {
+            // The corresponding window doesn't have a system menu, most likely due to the
+            // lack of the "WS_SYSMENU" window style. This situation should not be treated
+            // as an error so just ignore it and return early.
+            return;
+        }
+
+        const bool maxOrFull = IsMaximized(hWnd) || isFullScreen(hWnd);
+        ::EnableMenuItem(hMenu, SC_CLOSE, (MF_BYCOMMAND | MFS_ENABLED));
+        ::EnableMenuItem(hMenu, SC_MAXIMIZE,
+                         (MF_BYCOMMAND | ((maxOrFull || fixedSize) ? MFS_DISABLED : MFS_ENABLED)));
+        ::EnableMenuItem(hMenu, SC_RESTORE,
+                         (MF_BYCOMMAND | ((maxOrFull && !fixedSize) ? MFS_ENABLED : MFS_DISABLED)));
+        // The first menu item should be selected by default if the menu is brought
+        // up by keyboard. I don't know how to pre-select a menu item but it seems
+        // highlight can do the job. However, there's an annoying issue if we do
+        // this manually: the highlighted menu item is really only highlighted,
+        // not selected, so even if the mouse cursor hovers on other menu items
+        // or the user navigates to other menu items through keyboard, the original
+        // highlight bar will not move accordingly, the OS will generate another
+        // highlight bar to indicate the current selected menu item, which will make
+        // the menu look kind of weird. Currently I don't know how to fix this issue.
+        ::HiliteMenuItem(hWnd, hMenu, SC_RESTORE,
+                         (MF_BYCOMMAND | (selectFirstEntry ? MFS_HILITE : MFS_UNHILITE)));
+        ::EnableMenuItem(hMenu, SC_MINIMIZE, (MF_BYCOMMAND | MFS_ENABLED));
+        ::EnableMenuItem(hMenu, SC_SIZE,
+                         (MF_BYCOMMAND | ((maxOrFull || fixedSize) ? MFS_DISABLED : MFS_ENABLED)));
+        ::EnableMenuItem(hMenu, SC_MOVE, (MF_BYCOMMAND | (maxOrFull ? MFS_DISABLED : MFS_ENABLED)));
+
+        // The default menu item will appear in bold font. There can only be one default
+        // menu item per menu at most. Set the item ID to "UINT_MAX" (or simply "-1")
+        // can clear the default item for the given menu.
+        UINT defaultItemId = UINT_MAX;
+        if (isWin11OrGreater()) {
+            if (maxOrFull) {
+                defaultItemId = SC_RESTORE;
+            } else {
+                defaultItemId = SC_MAXIMIZE;
+            }
+        }
+        if (defaultItemId == UINT_MAX) {
+            defaultItemId = SC_CLOSE;
+        }
+        ::SetMenuDefaultItem(hMenu, defaultItemId, FALSE);
+
+        // Popup the system menu at the required position.
+        const auto result = ::TrackPopupMenu(
+            hMenu,
+            (TPM_RETURNCMD | (QGuiApplication::isRightToLeft() ? TPM_RIGHTALIGN : TPM_LEFTALIGN)),
+            pos.x, pos.y, 0, hWnd, nullptr);
+
+        // Unhighlight the first menu item after the popup menu is closed, otherwise it will keep
+        // highlighting until we unhighlight it manually.
+        ::HiliteMenuItem(hWnd, hMenu, SC_RESTORE, (MF_BYCOMMAND | MFS_UNHILITE));
+
+        if (!result) {
+            // The user canceled the menu, no need to continue.
+            return;
+        }
+
+        // Send the command that the user chooses to the corresponding window.
+        ::PostMessageW(hWnd, WM_SYSCOMMAND, result, 0);
     }
 
     static inline Win32WindowContext::WindowPart getHitWindowPart(int hitTestResult) {
@@ -367,7 +483,7 @@
     }
 
     static bool isValidWindow(HWND hWnd, bool checkVisible, bool checkTopLevel) {
-        if (::IsWindow(hWnd) == FALSE) {
+        if (!::IsWindow(hWnd)) {
             return false;
         }
         const LONG_PTR styles = ::GetWindowLongPtrW(hWnd, GWL_STYLE);
@@ -378,15 +494,15 @@
         if (exStyles & WS_EX_TOOLWINDOW) {
             return false;
         }
-        RECT rect = {0, 0, 0, 0};
-        if (::GetWindowRect(hWnd, &rect) == FALSE) {
+        RECT rect{};
+        if (!::GetWindowRect(hWnd, &rect)) {
             return false;
         }
         if ((rect.left >= rect.right) || (rect.top >= rect.bottom)) {
             return false;
         }
         if (checkVisible) {
-            if (::IsWindowVisible(hWnd) == FALSE) {
+            if (!::IsWindowVisible(hWnd)) {
                 return false;
             }
         }
@@ -405,41 +521,54 @@
     // DefWindowProc(). Consequently, we have to add a global native filter that forwards the result
     // of the hook function, telling Qt whether we have filtered the events before. Since Qt only
     // handles Windows window messages in the main thread, it is safe to do so.
-    class WindowsNativeEventFilter : public QAbstractNativeEventFilter {
+    class WindowsNativeEventFilter : public NativeEventFilter {
     public:
         bool nativeEventFilter(const QByteArray &eventType, void *message,
                                QT_NATIVE_EVENT_RESULT_TYPE *result) override {
+            Q_UNUSED(eventType)
+
             // It has been observed that the pointer that Qt gives us is sometimes null on some
             // machines. We need to guard against it in such scenarios.
             if (!result) {
                 return false;
             }
-            if (lastMessageHandled) {
-                *result = static_cast<QT_NATIVE_EVENT_RESULT_TYPE>(lastMessageResult);
-                return true;
+
+            // https://github.com/qt/qtbase/blob/e26a87f1ecc40bc8c6aa5b889fce67410a57a702/src/plugins/platforms/windows/qwindowscontext.cpp#L1546
+            // Qt needs to refer to the WM_NCCALCSIZE message data that hasn't been processed, so we
+            // have to process it after Qt acquires the initial data.
+            auto msg = static_cast<const MSG *>(message);
+            if (msg->message == WM_NCCALCSIZE && lastMessageContext) {
+                LRESULT res;
+                if (lastMessageContext->nonClientCalcSizeHandler(msg->hwnd, msg->message,
+                                                                 msg->wParam, msg->lParam, &res)) {
+                    *result = decltype(*result)(res);
+                    return true;
+                }
             }
             return false;
         }
 
-        static bool lastMessageHandled;
-        static LRESULT lastMessageResult;
         static WindowsNativeEventFilter *instance;
+        static Win32WindowContext *lastMessageContext;
 
         static inline void install() {
+            if (instance) {
+                return;
+            }
             instance = new WindowsNativeEventFilter();
-            installNativeEventFilter(instance);
         }
 
         static inline void uninstall() {
-            removeNativeEventFilter(instance);
+            if (!instance) {
+                return;
+            }
             delete instance;
             instance = nullptr;
         }
     };
 
-    bool WindowsNativeEventFilter::lastMessageHandled = false;
-    LRESULT WindowsNativeEventFilter::lastMessageResult = 0;
     WindowsNativeEventFilter *WindowsNativeEventFilter::instance = nullptr;
+    Win32WindowContext *WindowsNativeEventFilter::lastMessageContext = nullptr;
 
     // https://github.com/qt/qtbase/blob/e26a87f1ecc40bc8c6aa5b889fce67410a57a702/src/plugins/platforms/windows/qwindowscontext.cpp#L1025
     // We can see from the source code that Qt will filter out some messages first and then send the
@@ -506,21 +635,26 @@
             return ::DefWindowProcW(hWnd, message, wParam, lParam);
         }
 
+        // Since Qt does the necessary processing of the WM_NCCALCSIZE message, we need to
+        // forward it right away and process it in our native event filter.
+        if (message == WM_NCCALCSIZE) {
+            WindowsNativeEventFilter::lastMessageContext = ctx;
+            LRESULT result = ::CallWindowProcW(g_qtWindowProc, hWnd, message, wParam, lParam);
+            WindowsNativeEventFilter::lastMessageContext = nullptr;
+            return result;
+        }
+
         // Try hooked procedure and save result
-        auto &handled = WindowsNativeEventFilter::lastMessageHandled;
-        auto &result = WindowsNativeEventFilter::lastMessageResult;
-        handled = ctx->windowProc(hWnd, message, wParam, lParam, &result);
+        LRESULT result;
+        if (ctx->windowProc(hWnd, message, wParam, lParam, &result)) {
+            return result;
+        }
 
-        // TODO: Determine whether to show system menu
-        // ...
-
-        // Since Qt does the necessary processing of the message afterward, we still need to
-        // continue dispatching it.
+        // Continue dispatching.
         return ::CallWindowProcW(g_qtWindowProc, hWnd, message, wParam, lParam);
     }
 
-    Win32WindowContext::Win32WindowContext(QObject *host, WindowItemDelegate *delegate)
-        : AbstractWindowContext(host, delegate) {
+    Win32WindowContext::Win32WindowContext() : AbstractWindowContext() {
     }
 
     Win32WindowContext::~Win32WindowContext() {
@@ -535,11 +669,13 @@
         }
     }
 
-    bool Win32WindowContext::setup() {
-        if (!m_windowHandle) {
-            return false;
-        }
+    void Win32WindowContext::showSystemMenu(const QPoint &pos) {
+        auto winId = m_windowHandle->winId();
+        auto hWnd = reinterpret_cast<HWND>(winId);
+        showSystemMenu2(hWnd, {pos.x(), pos.y()}, false, m_delegate->isHostSizeFixed(m_host));
+    }
 
+    bool Win32WindowContext::setupHost() {
         // Install window hook
         auto winId = m_windowHandle->winId();
         auto hWnd = reinterpret_cast<HWND>(winId);
@@ -556,17 +692,13 @@
         ::SetWindowLongPtrW(hWnd, GWLP_WNDPROC, reinterpret_cast<LONG_PTR>(QWKHookedWndProc));
 
         // Install global native event filter
-        if (!WindowsNativeEventFilter::instance) {
-            WindowsNativeEventFilter::install();
-        }
+        WindowsNativeEventFilter::install();
 
         // Cache window ID
         windowId = winId;
 
         // Save window handle mapping
         g_wndProcHash->insert(hWnd, this);
-
-        QTimer::singleShot(0, m_windowHandle, [hWnd](){ triggerFrameChange(hWnd); });
 
         return true;
     }
@@ -603,6 +735,10 @@
             return true;
         }
 
+        if (systemMenuHandler(hWnd, message, wParam, lParam, result)) {
+            return true;
+        }
+
         return false; // Not handled
     }
 
@@ -617,7 +753,7 @@
         const auto &get = [](const int virtualKey) -> bool {
             return (::GetAsyncKeyState(virtualKey) < 0);
         };
-        const bool buttonSwapped = (::GetSystemMetrics(SM_SWAPBUTTON) != FALSE);
+        const bool buttonSwapped = ::GetSystemMetrics(SM_SWAPBUTTON);
         if (get(VK_LBUTTON)) {
             result |= (buttonSwapped ? MK_RBUTTON : MK_LBUTTON);
         }
@@ -760,10 +896,11 @@
                     // actually lost the hover state. So we filter out these superfluous mouse leave
                     // events here to avoid this issue.
                     DWORD dwScreenPos = ::GetMessagePos();
-                    QPoint qtScenePos =
-                        fromNativeLocalPosition(m_windowHandle, QPoint(GET_X_LPARAM(dwScreenPos),
-                                                                       GET_Y_LPARAM(dwScreenPos)));
-                    auto dummy = CoreWindowAgent::Unknown;
+                    POINT screenPoint{GET_X_LPARAM(dwScreenPos), GET_Y_LPARAM(dwScreenPos)};
+                    ::ScreenToClient(hWnd, &screenPoint);
+                    QPoint qtScenePos = QHighDpi::fromNativeLocalPosition(point2qpoint(screenPoint),
+                                                                          m_windowHandle);
+                    auto dummy = WindowAgentBase::Unknown;
                     if (isInSystemButtons(qtScenePos, &dummy)) {
                         // We must record whether the last WM_MOUSELEAVE was filtered, because if
                         // Qt does not receive this message it will not call TrackMouseEvent()
@@ -810,7 +947,7 @@
                 const WindowPart currentWindowPart = lastHitTestResult;
                 if (message == WM_NCMOUSEMOVE) {
                     if (currentWindowPart != WindowPart::ChromeButton) {
-                        std::ignore = m_delegate->resetQtGrabbedControl();
+                        m_delegate->resetQtGrabbedControl();
                         if (mouseLeaveBlocked) {
                             emulateClientAreaMessage(hWnd, message, wParam, lParam,
                                                      WM_NCMOUSELEAVE);
@@ -872,7 +1009,7 @@
                         // window from client area, which means we will get previous window part as
                         // HTCLIENT if the mouse leaves window from client area and enters window
                         // from non-client area, but it has no bad effect.
-                        std::ignore = m_delegate->resetQtGrabbedControl();
+                        m_delegate->resetQtGrabbedControl();
                     }
                 }
                 break;
@@ -887,232 +1024,17 @@
     bool Win32WindowContext::customWindowHandler(HWND hWnd, UINT message, WPARAM wParam,
                                                  LPARAM lParam, LRESULT *result) {
         switch (message) {
-            case WM_NCCALCSIZE: {
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-                // 鍜岄潪瀹㈡埛鍖猴紙鏍囬鏍忋�佺獥鍙h竟妗嗐�佽彍鍗曟爮鍜岀姸鎬佹爮绛塛indows绯荤粺鑷鎻愪緵鐨勯儴鍒�
-                // 锛屼笉杩囧浜嶲t鏉ヨ锛岄櫎浜嗘爣棰樻爮鍜岀獥鍙h竟妗嗭紝闈炲鎴峰尯鍩烘湰涔熼兘鏄嚜缁樼殑锛夌殑鑼�
-                // 鍥寸殑锛宭Param閲屽瓨鏀剧殑灏辨槸鏂板鎴峰尯鐨勫嚑浣曞尯鍩燂紝榛樿鏄暣涓獥鍙g殑澶у皬锛屾甯�
-                // 鐨勭▼搴忛渶瑕佷慨鏀硅繖涓弬鏁帮紝鍛婄煡绯荤粺绐楀彛鐨勫鎴峰尯鍜岄潪瀹㈡埛鍖虹殑鑼冨洿锛堜竴鑸潵璇村彲
-                // 浠ュ畬鍏ㄤ氦缁橶indows锛岃鍏惰嚜琛屽鐞嗭紝浣跨敤榛樿鐨勫鎴峰尯鍜岄潪瀹㈡埛鍖猴級锛屽洜姝ゅ鏋�
-                // 鎴戜滑涓嶄慨鏀筶Param锛屽氨鍙互浣垮鎴峰尯鍏呮弧鏁翠釜绐楀彛锛屼粠鑰屽幓鎺夋爣棰樻爮鍜岀獥鍙h竟妗�
-                // 锛堝洜涓鸿繖浜涗笢瑗块兘琚鎴峰尯缁欑洊浣忎簡銆備絾杈规闃村奖涔熶細鍥犳鑰屼涪澶憋紝涓嶈繃鎴戜滑浼氫娇
-                // 鐢ㄥ叾浠栨柟寮忓皢鍏跺甫鍥烇紝璇峰弬鑰冨叾浠栨秷鎭殑澶勭悊锛屾澶勪笉杩囧鎻愬強锛夈�備絾鏈変釜鎯呭喌瑕�
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-                // 鐢ㄦ埛鐪嬩笉鍒扮獥鍙g殑杈圭晫锛岃繖鏍风敤鎴峰氨涓嶈兘鍦ㄧ獥鍙f渶澶у寲鍚庤皟鏁寸獥鍙g殑澶у皬浜嗭紙铏界劧
-                // 杩欎釜鍋氭硶鍚捣鏉ョ壒鍒鎬紝浣哤indows纭疄灏辨槸杩欐牱鍋氱殑锛夛紝鍥犳濡傛灉鎴戜滑瑕佽嚜琛�
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-                // 绛夌殑锛変粠瀹㈡埛鍖鸿鍓帀锛屽惁鍒欐垜浠獥鍙f墍鏄剧ず鐨勫唴瀹瑰氨浼氳秴鍑哄睆骞曡竟鐣岋紝鏄剧ず涓嶅叏銆�
-                // 濡傛灉鐢ㄦ埛寮�鍚簡浠诲姟鏍忚嚜鍔ㄩ殣钘忥紝鍦ㄧ獥鍙f渶澶у寲鍚庯紝杩樿鑰冭檻浠诲姟鏍忕殑浣嶇疆銆傚洜涓�
-                // 濡傛灉绐楀彛鏈�澶у寲鍚庯紝鍏跺昂瀵稿拰灞忓箷灏哄鐩哥瓑锛堝洜涓轰换鍔℃爮闅愯棌浜嗭紝鎵�浠ョ獥鍙f渶澶у寲
-                // 鍚庡叾瀹炴槸鍏呮弧浜嗘暣涓睆骞曪紝鍙樼浉鐨勫叏灞忎簡锛夛紝Windows浼氳涓虹獥鍙e凡缁忚繘鍏ュ叏灞忕殑
-                // 鐘舵�侊紝浠庤�屽鑷磋嚜鍔ㄩ殣钘忕殑浠诲姟鏍忔棤娉曞脊鍑恒�傝閬垮厤杩欎釜鐘跺喌锛屽氨瑕佷娇绐楀彛鐨勫昂瀵�
-                // 灏忎簬灞忓箷灏哄銆傛垜涓嬮潰鐨勫仛娉曞弬鑰冧簡鐏嫄銆丆hromium鍜學indows Terminal
-                // 濡傛灉娌℃湁寮�鍚换鍔℃爮鑷姩闅愯棌锛屾槸涓嶅瓨鍦ㄨ繖涓棶棰樼殑锛屾墍浠ヨ鍏堣繘琛屽垽鏂��
-                // 涓�鑸儏鍐典笅锛�*result璁剧疆涓�0锛堢浉褰撲簬DefWindowProc鐨勮繑鍥炲�间负0锛夊氨鍙互浜嗭紝
-                // 鏍规嵁MSDN鐨勮娉曪紝杩斿洖0鎰忎负姝ゆ秷鎭凡缁忚绋嬪簭鑷澶勭悊浜嗭紝璁¦indows璺宠繃姝ゆ秷
-                // 鎭紝鍚﹀垯Windows浼氭坊鍔犲姝ゆ秷鎭殑榛樿澶勭悊锛屽浜庡綋鍓嶈繖涓秷鎭�岃█锛屽氨鎰忓懗鐫�
-                // 鏍囬鏍忓拰绐楀彛杈规鍙堜細鍥炴潵锛岃繖褰撶劧涓嶆槸鎴戜滑鎯宠鐨勭粨鏋溿�傛牴鎹甅SDN锛屽綋wParam
-                // 涓篎ALSE鏃讹紝鍙兘杩斿洖0锛屼絾褰撳叾涓篢RUE鏃讹紝鍙互杩斿洖0锛屼篃鍙互杩斿洖涓�涓猈VR_甯�
-                // 閲忋�傛牴鎹瓹hromium鐨勬敞閲婏紝褰撳瓨鍦ㄩ潪瀹㈡埛鍖烘椂锛屽鏋滆繑鍥濿VR_REDRAW浼氬鑷村瓙
-                // 绐楀彛/瀛愭帶浠跺嚭鐜板鎬殑bug锛堣嚜缁樻帶浠堕敊浣嶏級锛屽苟涓擫ucas鍦╓indows 10
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-                // WVR_REDRAW锛屽惁鍒欑獥鍙e湪璋冩暣澶у皬鍙兘浼氫骇鐢熶弗閲嶇殑闂儊鐜拌薄銆�
-                // 铏界劧瀵瑰ぇ澶氭暟娑堟伅鏉ヨ锛岃繑鍥�0閮戒唬琛ㄨWindows蹇界暐姝ゆ秷鎭紝浣嗗疄闄呬笂涓嶅悓娑堟伅
-                // 鑳芥帴鍙楃殑杩斿洖鍊兼槸涓嶄竴鏍风殑锛岃娉ㄦ剰鑷鏌ラ槄MSDN銆�
-
-                // Sent when the size and position of a window's client area must be
-                // calculated. By processing this message, an application can
-                // control the content of the window's client area when the size or
-                // position of the window changes. If wParam is TRUE, lParam points
-                // to an NCCALCSIZE_PARAMS structure that contains information an
-                // application can use to calculate the new size and position of the
-                // client rectangle. If wParam is FALSE, lParam points to a RECT
-                // structure. On entry, the structure contains the proposed window
-                // rectangle for the window. On exit, the structure should contain
-                // the screen coordinates of the corresponding window client area.
-                // The client area is the window's content area, the non-client area
-                // is the area which is provided by the system, such as the title
-                // bar, the four window borders, the frame shadow, the menu bar, the
-                // status bar, the scroll bar, etc. But for Qt, it draws most of the
-                // window area (client + non-client) itself. We now know that the
-                // title bar and the window frame is in the non-client area, and we
-                // can set the scope of the client area in this message, so we can
-                // remove the title bar and the window frame by let the non-client
-                // area be covered by the client area (because we can't really get
-                // rid of the non-client area, it will always be there, all we can
-                // do is to hide it) , which means we should let the client area's
-                // size the same with the whole window's size. So there is no room
-                // for the non-client area and then the user won't be able to see it
-                // again. But how to achieve this? Very easy, just leave lParam (the
-                // re-calculated client area) untouched. But of course you can
-                // modify lParam, then the non-client area will be seen and the
-                // window borders and the window frame will show up. However, things
-                // are quite different when you try to modify the top margin of the
-                // client area. DWM will always draw the whole title bar no matter
-                // what margin value you set for the top, unless you don't modify it
-                // and remove the whole top area (the title bar + the one pixel
-                // height window border). This can be confirmed in Windows
-                // Terminal's source code, you can also try yourself to verify
-                // it. So things will become quite complicated if you want to
-                // preserve the four window borders.
-
-                // If `wParam` is `FALSE`, `lParam` points to a `RECT` that contains
-                // the proposed window rectangle for our window. During our
-                // processing of the `WM_NCCALCSIZE` message, we are expected to
-                // modify the `RECT` that `lParam` points to, so that its value upon
-                // our return is the new client area. We must return 0 if `wParam`
-                // is `FALSE`.
-                // If `wParam` is `TRUE`, `lParam` points to a `NCCALCSIZE_PARAMS`
-                // struct. This struct contains an array of 3 `RECT`s, the first of
-                // which has the exact same meaning as the `RECT` that is pointed to
-                // by `lParam` when `wParam` is `FALSE`. The remaining `RECT`s, in
-                // conjunction with our return value, can
-                // be used to specify portions of the source and destination window
-                // rectangles that are valid and should be preserved. We opt not to
-                // implement an elaborate client-area preservation technique, and
-                // simply return 0, which means "preserve the entire old client area
-                // and align it with the upper-left corner of our new client area".
-                const auto clientRect =
-                    ((wParam == FALSE) ? reinterpret_cast<LPRECT>(lParam)
-                                       : &(reinterpret_cast<LPNCCALCSIZE_PARAMS>(lParam))->rgrc[0]);
-                if (isWin10OrGreater()) {
-                    // Store the original top margin before the default window procedure applies the
-                    // default frame.
-                    const LONG originalTop = clientRect->top;
-                    // Apply the default frame because we don't want to remove the whole window
-                    // frame, we still need the standard window frame (the resizable frame border
-                    // and the frame shadow) for the left, bottom and right edges. If we return 0
-                    // here directly, the whole window frame will be removed (which means there will
-                    // be no resizable frame border and the frame shadow will also disappear), and
-                    // that's also how most applications customize their title bars on Windows. It's
-                    // totally OK but since we want to preserve as much original frame as possible,
-                    // we can't use that solution.
-                    const LRESULT hitTestResult =
-                        ::DefWindowProcW(hWnd, WM_NCCALCSIZE, wParam, lParam);
-                    if ((hitTestResult != HTERROR) && (hitTestResult != HTNOWHERE)) {
-                        *result = hitTestResult;
-                        return true;
-                    }
-                    // Re-apply the original top from before the size of the default frame was
-                    // applied, and the whole top frame (the title bar and the top border) is gone
-                    // now. For the top frame, we only has 2 choices: (1) remove the top frame
-                    // entirely, or (2) don't touch it at all. We can't preserve the top border by
-                    // adjusting the top margin here. If we try to modify the top margin, the
-                    // original title bar will always be painted by DWM regardless what margin we
-                    // set, so here we can only remove the top frame entirely and use some special
-                    // technique to bring the top border back.
-                    clientRect->top = originalTop;
-                }
-                const bool max = IsMaximized(hWnd);
-                const bool full = isFullScreen(hWnd);
-                // We don't need this correction when we're fullscreen. We will
-                // have the WS_POPUP size, so we don't have to worry about
-                // borders, and the default frame will be fine.
-                if (max && !full) {
-                    // When a window is maximized, its size is actually a little bit more
-                    // than the monitor's work area. The window is positioned and sized in
-                    // such a way that the resize handles are outside the monitor and
-                    // then the window is clipped to the monitor so that the resize handle
-                    // do not appear because you don't need them (because you can't resize
-                    // a window when it's maximized unless you restore it).
-                    const quint32 frameSize = getResizeBorderThickness(hWnd);
-                    clientRect->top += frameSize;
-                    if (!isWin10OrGreater()) {
-                        clientRect->bottom -= frameSize;
-                        clientRect->left += frameSize;
-                        clientRect->right -= frameSize;
+            case WM_SHOWWINDOW: {
+                if (!centered) {
+                    // If wParam is TRUE, the window is being shown.
+                    // If lParam is zero, the message was sent because of a call to the ShowWindow
+                    // function.
+                    if (wParam && lParam == 0) {
+                        centered = true;
+                        moveToDesktopCenter(hWnd);
                     }
                 }
-                // Attempt to detect if there's an autohide taskbar, and if
-                // there is, reduce our size a bit on the side with the taskbar,
-                // so the user can still mouse-over the taskbar to reveal it.
-                // Make sure to use MONITOR_DEFAULTTONEAREST, so that this will
-                // still find the right monitor even when we're restoring from
-                // minimized.
-                if (max || full) {
-                    APPBARDATA abd{};
-                    abd.cbSize = sizeof(abd);
-                    const UINT taskbarState = ::SHAppBarMessage(ABM_GETSTATE, &abd);
-                    // First, check if we have an auto-hide taskbar at all:
-                    if (taskbarState & ABS_AUTOHIDE) {
-                        bool top = false, bottom = false, left = false, right = false;
-                        // Due to ABM_GETAUTOHIDEBAREX was introduced in Windows 8.1,
-                        // we have to use another way to judge this if we are running
-                        // on Windows 7 or Windows 8.
-                        if (isWin8Point1OrGreater()) {
-                            const std::optional<MONITORINFOEXW> monitorInfo =
-                                getMonitorForWindow(hWnd);
-                            const RECT monitorRect = monitorInfo.value().rcMonitor;
-                            // This helper can be used to determine if there's an
-                            // auto-hide taskbar on the given edge of the monitor
-                            // we're currently on.
-                            const auto hasAutohideTaskbar = [monitorRect](const UINT edge) -> bool {
-                                APPBARDATA abd2{};
-                                abd2.cbSize = sizeof(abd2);
-                                abd2.uEdge = edge;
-                                abd2.rc = monitorRect;
-                                const auto hTaskbar = reinterpret_cast<HWND>(
-                                    ::SHAppBarMessage(ABM_GETAUTOHIDEBAREX, &abd2));
-                                return (hTaskbar != nullptr);
-                            };
-                            top = hasAutohideTaskbar(ABE_TOP);
-                            bottom = hasAutohideTaskbar(ABE_BOTTOM);
-                            left = hasAutohideTaskbar(ABE_LEFT);
-                            right = hasAutohideTaskbar(ABE_RIGHT);
-                        } else {
-                            int edge = -1;
-                            APPBARDATA abd2{};
-                            abd2.cbSize = sizeof(abd2);
-                            abd2.hWnd = ::FindWindowW(L"Shell_TrayWnd", nullptr);
-                            HMONITOR windowMonitor =
-                                ::MonitorFromWindow(hWnd, MONITOR_DEFAULTTONEAREST);
-                            HMONITOR taskbarMonitor =
-                                ::MonitorFromWindow(abd2.hWnd, MONITOR_DEFAULTTOPRIMARY);
-                            if (taskbarMonitor == windowMonitor) {
-                                ::SHAppBarMessage(ABM_GETTASKBARPOS, &abd2);
-                                edge = int(abd2.uEdge);
-                            }
-                            top = (edge == ABE_TOP);
-                            bottom = (edge == ABE_BOTTOM);
-                            left = (edge == ABE_LEFT);
-                            right = (edge == ABE_RIGHT);
-                        }
-                        // If there's a taskbar on any side of the monitor, reduce
-                        // our size a little bit on that edge.
-                        // Note to future code archeologists:
-                        // This doesn't seem to work for fullscreen on the primary
-                        // display. However, testing a bunch of other apps with
-                        // fullscreen modes and an auto-hiding taskbar has
-                        // shown that _none_ of them reveal the taskbar from
-                        // fullscreen mode. This includes Edge, Firefox, Chrome,
-                        // Sublime Text, PowerPoint - none seemed to support this.
-                        // This does however work fine for maximized.
-                        if (top) {
-                            // Peculiarly, when we're fullscreen,
-                            clientRect->top += kAutoHideTaskBarThickness;
-                        } else if (bottom) {
-                            clientRect->bottom -= kAutoHideTaskBarThickness;
-                        } else if (left) {
-                            clientRect->left += kAutoHideTaskBarThickness;
-                        } else if (right) {
-                            clientRect->right -= kAutoHideTaskBarThickness;
-                        }
-                    }
-                }
-                // ### TODO: std::ignore = Utils::syncWmPaintWithDwm(); // This should be executed
-                // at the very last. By returning WVR_REDRAW we can make the window resizing look
-                // less broken. But we must return 0 if wParam is FALSE, according to Microsoft
-                // Docs.
-                // **IMPORTANT NOTE**:
-                // If you are drawing something manually through D3D in your window, don't
-                // try to return WVR_REDRAW here, otherwise Windows exhibits bugs where
-                // client pixels and child windows are mispositioned by the width/height
-                // of the upper-left non-client area. It's confirmed that this issue exists
-                // from Windows 7 to Windows 10. Not tested on Windows 11 yet. Don't know
-                // whether it exists on Windows XP to Windows Vista or not.
-                *result = wParam == FALSE ? FALSE : WVR_REDRAW;
-                return true;
+                break;
             }
             case WM_NCHITTEST: {
                 // 鍘熺敓Win32绐楀彛鍙湁椤惰竟鏄湪绐楀彛鍐呴儴resize鐨勶紝鍏朵綑涓夎竟閮芥槸鍦ㄧ獥鍙�
@@ -1209,14 +1131,14 @@
                 auto clientWidth = RECT_WIDTH(clientRect);
                 auto clientHeight = RECT_HEIGHT(clientRect);
 
-                QPoint qtScenePos = fromNativeLocalPosition(
-                    m_windowHandle, QPoint(nativeLocalPos.x, nativeLocalPos.y));
+                QPoint qtScenePos =
+                    QHighDpi::fromNativeLocalPosition(point2qpoint(nativeLocalPos), m_windowHandle);
 
                 bool isFixedSize = m_delegate->isHostSizeFixed(m_host);
                 bool isTitleBar = isInTitleBarDraggableArea(qtScenePos);
-                bool dontOverrideCursor = false;                  // ### TODO
+                bool dontOverrideCursor = false; // ### TODO
 
-                CoreWindowAgent::SystemButton sysButtonType = CoreWindowAgent::Unknown;
+                WindowAgentBase::SystemButton sysButtonType = WindowAgentBase::Unknown;
                 if (!isFixedSize && isInSystemButtons(qtScenePos, &sysButtonType)) {
                     // Firstly, we set the hit test result to a default value to be able to detect
                     // whether we have changed it or not afterwards.
@@ -1226,22 +1148,31 @@
                     // this is also the normal behavior of a native Win32 window (but only when the
                     // window is not maximized/fullscreen/minimized, of course).
                     if (isWindowNoState(hWnd)) {
-                        static constexpr const int kBorderSize = 2;
+                        static constexpr const auto kBorderSize = quint8{2};
                         bool isTop = (nativeLocalPos.y <= kBorderSize);
+                        bool isLeft = nativeLocalPos.x <= kBorderSize;
                         bool isRight = (nativeLocalPos.x >= (clientWidth - kBorderSize));
-                        if (isTop || isRight) {
+                        if (isTop || isLeft || isRight) {
                             if (dontOverrideCursor) {
                                 // The user doesn't want the window to be resized, so we tell
                                 // Windows we are in the client area so that the controls beneath
                                 // the mouse cursor can still be hovered or clicked.
                                 *result = (isTitleBar ? HTCAPTION : HTCLIENT);
                             } else {
-                                if (isTop && isRight) {
-                                    *result = HTTOPRIGHT;
-                                } else if (isTop) {
-                                    *result = HTTOP;
+                                if (isTop) {
+                                    if (isLeft) {
+                                        *result = HTTOPLEFT;
+                                    } else if (isRight) {
+                                        *result = HTTOPRIGHT;
+                                    } else {
+                                        *result = HTTOP;
+                                    }
                                 } else {
-                                    *result = HTRIGHT;
+                                    if (isLeft) {
+                                        *result = HTLEFT;
+                                    } else {
+                                        *result = HTRIGHT;
+                                    }
                                 }
                             }
                         }
@@ -1251,22 +1182,20 @@
                         // exact role of our button. The Snap Layout feature introduced in Windows
                         // 11 won't work without this.
                         switch (sysButtonType) {
-                            case CoreWindowAgent::WindowIcon:
+                            case WindowAgentBase::WindowIcon:
                                 *result = HTSYSMENU;
                                 break;
-                            case CoreWindowAgent::Help:
+                            case WindowAgentBase::Help:
                                 *result = HTHELP;
                                 break;
-                            case CoreWindowAgent::Minimize:
+                            case WindowAgentBase::Minimize:
                                 *result = HTREDUCE;
                                 break;
-                            case CoreWindowAgent::Maximize:
+                            case WindowAgentBase::Maximize:
                                 *result = HTZOOM;
                                 break;
-                            case CoreWindowAgent::Close:
+                            case WindowAgentBase::Close:
                                 *result = HTCLOSE;
-                                break;
-                            case CoreWindowAgent::Unknown:
                                 break;
                             default:
                                 break; // unreachable
@@ -1329,6 +1258,7 @@
                         return true;
                     }
                     *result = HTCLIENT;
+                    return true;
                 } else {
                     if (full) {
                         *result = HTCLIENT;
@@ -1342,9 +1272,9 @@
                         const bool isBottom = (nativeLocalPos.y >= (clientHeight - frameSize));
                         // Make the border a little wider to let the user easy to resize on corners.
                         const auto scaleFactor = ((isTop || isBottom) ? qreal(2) : qreal(1));
-                        const int scaledFrameSizeX = std::round(qreal(frameSize) * scaleFactor);
-                        const bool isLeft = (nativeLocalPos.x < scaledFrameSizeX);
-                        const bool isRight = (nativeLocalPos.x >= (clientWidth - scaledFrameSizeX));
+                        const int scaledFrameSize = std::round(qreal(frameSize) * scaleFactor);
+                        const bool isLeft = (nativeLocalPos.x < scaledFrameSize);
+                        const bool isRight = (nativeLocalPos.x >= (clientWidth - scaledFrameSize));
                         if (dontOverrideCursor && (isTop || isBottom || isLeft || isRight)) {
                             // Return HTCLIENT instead of HTBORDER here, because the mouse is
                             // inside the window now, return HTCLIENT to let the controls
@@ -1390,8 +1320,8 @@
                         return true;
                     }
                     *result = HTCLIENT;
+                    return true;
                 }
-                return true;
             }
             default:
                 break;
@@ -1428,10 +1358,10 @@
                         // window activation state change.
                         *result = ::DefWindowProcW(hWnd, WM_NCACTIVATE, wParam, -1);
                     } else {
-                        if (wParam == FALSE) {
-                            *result = TRUE;
-                        } else {
+                        if (wParam) {
                             *result = FALSE;
+                        } else {
+                            *result = TRUE;
                         }
                     }
                     return true;
@@ -1459,4 +1389,320 @@
         return false;
     }
 
-}
\ No newline at end of file
+    bool Win32WindowContext::nonClientCalcSizeHandler(HWND hWnd, UINT message, WPARAM wParam,
+                                                      LPARAM lParam, LRESULT *result) {
+        Q_UNUSED(message)
+        Q_UNUSED(this)
+
+        // Windows鏄牴鎹繖涓秷鎭殑杩斿洖鍊兼潵璁剧疆绐楀彛鐨勫鎴峰尯锛堢獥鍙d腑鐪熸鏄剧ず鐨勫唴瀹癸級
+        // 鍜岄潪瀹㈡埛鍖猴紙鏍囬鏍忋�佺獥鍙h竟妗嗐�佽彍鍗曟爮鍜岀姸鎬佹爮绛塛indows绯荤粺鑷鎻愪緵鐨勯儴鍒�
+        // 锛屼笉杩囧浜嶲t鏉ヨ锛岄櫎浜嗘爣棰樻爮鍜岀獥鍙h竟妗嗭紝闈炲鎴峰尯鍩烘湰涔熼兘鏄嚜缁樼殑锛夌殑鑼�
+        // 鍥寸殑锛宭Param閲屽瓨鏀剧殑灏辨槸鏂板鎴峰尯鐨勫嚑浣曞尯鍩燂紝榛樿鏄暣涓獥鍙g殑澶у皬锛屾甯�
+        // 鐨勭▼搴忛渶瑕佷慨鏀硅繖涓弬鏁帮紝鍛婄煡绯荤粺绐楀彛鐨勫鎴峰尯鍜岄潪瀹㈡埛鍖虹殑鑼冨洿锛堜竴鑸潵璇村彲
+        // 浠ュ畬鍏ㄤ氦缁橶indows锛岃鍏惰嚜琛屽鐞嗭紝浣跨敤榛樿鐨勫鎴峰尯鍜岄潪瀹㈡埛鍖猴級锛屽洜姝ゅ鏋�
+        // 鎴戜滑涓嶄慨鏀筶Param锛屽氨鍙互浣垮鎴峰尯鍏呮弧鏁翠釜绐楀彛锛屼粠鑰屽幓鎺夋爣棰樻爮鍜岀獥鍙h竟妗�
+        // 锛堝洜涓鸿繖浜涗笢瑗块兘琚鎴峰尯缁欑洊浣忎簡銆備絾杈规闃村奖涔熶細鍥犳鑰屼涪澶憋紝涓嶈繃鎴戜滑浼氫娇
+        // 鐢ㄥ叾浠栨柟寮忓皢鍏跺甫鍥烇紝璇峰弬鑰冨叾浠栨秷鎭殑澶勭悊锛屾澶勪笉杩囧鎻愬強锛夈�備絾鏈変釜鎯呭喌瑕�
+        // 鐗瑰埆娉ㄦ剰锛岄偅灏辨槸绐楀彛鏈�澶у寲鍚庯紝绐楀彛鐨勫疄闄呭昂瀵镐細姣斿睆骞曠殑灏哄澶т竴鐐癸紝浠庤�屼娇
+        // 鐢ㄦ埛鐪嬩笉鍒扮獥鍙g殑杈圭晫锛岃繖鏍风敤鎴峰氨涓嶈兘鍦ㄧ獥鍙f渶澶у寲鍚庤皟鏁寸獥鍙g殑澶у皬浜嗭紙铏界劧
+        // 杩欎釜鍋氭硶鍚捣鏉ョ壒鍒鎬紝浣哤indows纭疄灏辨槸杩欐牱鍋氱殑锛夛紝鍥犳濡傛灉鎴戜滑瑕佽嚜琛�
+        // 澶勭悊绐楀彛鐨勯潪瀹㈡埛鍖猴紝灏辫鍦ㄧ獥鍙f渶澶у寲鍚庯紝灏嗙獥鍙h竟妗嗙殑瀹藉害鍜岄珮搴︼紙涓�鑸槸鐩�
+        // 绛夌殑锛変粠瀹㈡埛鍖鸿鍓帀锛屽惁鍒欐垜浠獥鍙f墍鏄剧ず鐨勫唴瀹瑰氨浼氳秴鍑哄睆骞曡竟鐣岋紝鏄剧ず涓嶅叏銆�
+        // 濡傛灉鐢ㄦ埛寮�鍚簡浠诲姟鏍忚嚜鍔ㄩ殣钘忥紝鍦ㄧ獥鍙f渶澶у寲鍚庯紝杩樿鑰冭檻浠诲姟鏍忕殑浣嶇疆銆傚洜涓�
+        // 濡傛灉绐楀彛鏈�澶у寲鍚庯紝鍏跺昂瀵稿拰灞忓箷灏哄鐩哥瓑锛堝洜涓轰换鍔℃爮闅愯棌浜嗭紝鎵�浠ョ獥鍙f渶澶у寲
+        // 鍚庡叾瀹炴槸鍏呮弧浜嗘暣涓睆骞曪紝鍙樼浉鐨勫叏灞忎簡锛夛紝Windows浼氳涓虹獥鍙e凡缁忚繘鍏ュ叏灞忕殑
+        // 鐘舵�侊紝浠庤�屽鑷磋嚜鍔ㄩ殣钘忕殑浠诲姟鏍忔棤娉曞脊鍑恒�傝閬垮厤杩欎釜鐘跺喌锛屽氨瑕佷娇绐楀彛鐨勫昂瀵�
+        // 灏忎簬灞忓箷灏哄銆傛垜涓嬮潰鐨勫仛娉曞弬鑰冧簡鐏嫄銆丆hromium鍜學indows Terminal
+        // 濡傛灉娌℃湁寮�鍚换鍔℃爮鑷姩闅愯棌锛屾槸涓嶅瓨鍦ㄨ繖涓棶棰樼殑锛屾墍浠ヨ鍏堣繘琛屽垽鏂��
+        // 涓�鑸儏鍐典笅锛�*result璁剧疆涓�0锛堢浉褰撲簬DefWindowProc鐨勮繑鍥炲�间负0锛夊氨鍙互浜嗭紝
+        // 鏍规嵁MSDN鐨勮娉曪紝杩斿洖0鎰忎负姝ゆ秷鎭凡缁忚绋嬪簭鑷澶勭悊浜嗭紝璁¦indows璺宠繃姝ゆ秷
+        // 鎭紝鍚﹀垯Windows浼氭坊鍔犲姝ゆ秷鎭殑榛樿澶勭悊锛屽浜庡綋鍓嶈繖涓秷鎭�岃█锛屽氨鎰忓懗鐫�
+        // 鏍囬鏍忓拰绐楀彛杈规鍙堜細鍥炴潵锛岃繖褰撶劧涓嶆槸鎴戜滑鎯宠鐨勭粨鏋溿�傛牴鎹甅SDN锛屽綋wParam
+        // 涓篎ALSE鏃讹紝鍙兘杩斿洖0锛屼絾褰撳叾涓篢RUE鏃讹紝鍙互杩斿洖0锛屼篃鍙互杩斿洖涓�涓猈VR_甯�
+        // 閲忋�傛牴鎹瓹hromium鐨勬敞閲婏紝褰撳瓨鍦ㄩ潪瀹㈡埛鍖烘椂锛屽鏋滆繑鍥濿VR_REDRAW浼氬鑷村瓙
+        // 绐楀彛/瀛愭帶浠跺嚭鐜板鎬殑bug锛堣嚜缁樻帶浠堕敊浣嶏級锛屽苟涓擫ucas鍦╓indows 10
+        // 涓婃垚鍔熷鐜帮紝璇存槑杩欎釜bug鑷充粖閮芥病鏈夎В鍐炽�傛垜鏌ラ槄浜嗗ぇ閲忚祫鏂欙紝鍙戠幇鍞竴鐨勮В鍐�
+        // 鏂规灏辨槸杩斿洖0銆備絾濡傛灉涓嶅瓨鍦ㄩ潪瀹㈡埛鍖猴紝涓攚Param涓篢RUE锛屾渶濂借繑鍥�
+        // WVR_REDRAW锛屽惁鍒欑獥鍙e湪璋冩暣澶у皬鍙兘浼氫骇鐢熶弗閲嶇殑闂儊鐜拌薄銆�
+        // 铏界劧瀵瑰ぇ澶氭暟娑堟伅鏉ヨ锛岃繑鍥�0閮戒唬琛ㄨWindows蹇界暐姝ゆ秷鎭紝浣嗗疄闄呬笂涓嶅悓娑堟伅
+        // 鑳芥帴鍙楃殑杩斿洖鍊兼槸涓嶄竴鏍风殑锛岃娉ㄦ剰鑷鏌ラ槄MSDN銆�
+
+        // Sent when the size and position of a window's client area must be
+        // calculated. By processing this message, an application can
+        // control the content of the window's client area when the size or
+        // position of the window changes. If wParam is TRUE, lParam points
+        // to an NCCALCSIZE_PARAMS structure that contains information an
+        // application can use to calculate the new size and position of the
+        // client rectangle. If wParam is FALSE, lParam points to a RECT
+        // structure. On entry, the structure contains the proposed window
+        // rectangle for the window. On exit, the structure should contain
+        // the screen coordinates of the corresponding window client area.
+        // The client area is the window's content area, the non-client area
+        // is the area which is provided by the system, such as the title
+        // bar, the four window borders, the frame shadow, the menu bar, the
+        // status bar, the scroll bar, etc. But for Qt, it draws most of the
+        // window area (client + non-client) itself. We now know that the
+        // title bar and the window frame is in the non-client area, and we
+        // can set the scope of the client area in this message, so we can
+        // remove the title bar and the window frame by let the non-client
+        // area be covered by the client area (because we can't really get
+        // rid of the non-client area, it will always be there, all we can
+        // do is to hide it) , which means we should let the client area's
+        // size the same with the whole window's size. So there is no room
+        // for the non-client area and then the user won't be able to see it
+        // again. But how to achieve this? Very easy, just leave lParam (the
+        // re-calculated client area) untouched. But of course you can
+        // modify lParam, then the non-client area will be seen and the
+        // window borders and the window frame will show up. However, things
+        // are quite different when you try to modify the top margin of the
+        // client area. DWM will always draw the whole title bar no matter
+        // what margin value you set for the top, unless you don't modify it
+        // and remove the whole top area (the title bar + the one pixel
+        // height window border). This can be confirmed in Windows
+        // Terminal's source code, you can also try yourself to verify
+        // it. So things will become quite complicated if you want to
+        // preserve the four window borders.
+
+        // If `wParam` is `FALSE`, `lParam` points to a `RECT` that contains
+        // the proposed window rectangle for our window. During our
+        // processing of the `WM_NCCALCSIZE` message, we are expected to
+        // modify the `RECT` that `lParam` points to, so that its value upon
+        // our return is the new client area. We must return 0 if `wParam`
+        // is `FALSE`.
+        // If `wParam` is `TRUE`, `lParam` points to a `NCCALCSIZE_PARAMS`
+        // struct. This struct contains an array of 3 `RECT`s, the first of
+        // which has the exact same meaning as the `RECT` that is pointed to
+        // by `lParam` when `wParam` is `FALSE`. The remaining `RECT`s, in
+        // conjunction with our return value, can
+        // be used to specify portions of the source and destination window
+        // rectangles that are valid and should be preserved. We opt not to
+        // implement an elaborate client-area preservation technique, and
+        // simply return 0, which means "preserve the entire old client area
+        // and align it with the upper-left corner of our new client area".
+        const auto clientRect = wParam ? &(reinterpret_cast<LPNCCALCSIZE_PARAMS>(lParam))->rgrc[0]
+                                       : reinterpret_cast<LPRECT>(lParam);
+        if (isWin10OrGreater()) {
+            // Store the original top margin before the default window procedure applies the
+            // default frame.
+            const LONG originalTop = clientRect->top;
+            // Apply the default frame because we don't want to remove the whole window
+            // frame, we still need the standard window frame (the resizable frame border
+            // and the frame shadow) for the left, bottom and right edges. If we return 0
+            // here directly, the whole window frame will be removed (which means there will
+            // be no resizable frame border and the frame shadow will also disappear), and
+            // that's also how most applications customize their title bars on Windows. It's
+            // totally OK but since we want to preserve as much original frame as possible,
+            // we can't use that solution.
+            const LRESULT hitTestResult = ::DefWindowProcW(hWnd, WM_NCCALCSIZE, wParam, lParam);
+            if ((hitTestResult != HTERROR) && (hitTestResult != HTNOWHERE)) {
+                *result = hitTestResult;
+                return true;
+            }
+            // Re-apply the original top from before the size of the default frame was
+            // applied, and the whole top frame (the title bar and the top border) is gone
+            // now. For the top frame, we only has 2 choices: (1) remove the top frame
+            // entirely, or (2) don't touch it at all. We can't preserve the top border by
+            // adjusting the top margin here. If we try to modify the top margin, the
+            // original title bar will always be painted by DWM regardless what margin we
+            // set, so here we can only remove the top frame entirely and use some special
+            // technique to bring the top border back.
+            clientRect->top = originalTop;
+        }
+        const bool max = IsMaximized(hWnd);
+        const bool full = isFullScreen(hWnd);
+        // We don't need this correction when we're fullscreen. We will
+        // have the WS_POPUP size, so we don't have to worry about
+        // borders, and the default frame will be fine.
+        if (max && !full) {
+            // When a window is maximized, its size is actually a little bit more
+            // than the monitor's work area. The window is positioned and sized in
+            // such a way that the resize handles are outside the monitor and
+            // then the window is clipped to the monitor so that the resize handle
+            // do not appear because you don't need them (because you can't resize
+            // a window when it's maximized unless you restore it).
+            const quint32 frameSize = getResizeBorderThickness(hWnd);
+            clientRect->top += frameSize;
+            if (!isWin10OrGreater()) {
+                clientRect->bottom -= frameSize;
+                clientRect->left += frameSize;
+                clientRect->right -= frameSize;
+            }
+        }
+        // Attempt to detect if there's an autohide taskbar, and if
+        // there is, reduce our size a bit on the side with the taskbar,
+        // so the user can still mouse-over the taskbar to reveal it.
+        // Make sure to use MONITOR_DEFAULTTONEAREST, so that this will
+        // still find the right monitor even when we're restoring from
+        // minimized.
+        if (max || full) {
+            APPBARDATA abd{};
+            abd.cbSize = sizeof(abd);
+            const UINT taskbarState = ::SHAppBarMessage(ABM_GETSTATE, &abd);
+            // First, check if we have an auto-hide taskbar at all:
+            if (taskbarState & ABS_AUTOHIDE) {
+                bool top = false, bottom = false, left = false, right = false;
+                // Due to ABM_GETAUTOHIDEBAREX was introduced in Windows 8.1,
+                // we have to use another way to judge this if we are running
+                // on Windows 7 or Windows 8.
+                if (isWin8Point1OrGreater()) {
+                    const RECT monitorRect = getMonitorForWindow(hWnd).rcMonitor;
+                    // This helper can be used to determine if there's an
+                    // auto-hide taskbar on the given edge of the monitor
+                    // we're currently on.
+                    const auto hasAutohideTaskbar = [monitorRect](const UINT edge) -> bool {
+                        APPBARDATA abd2{};
+                        abd2.cbSize = sizeof(abd2);
+                        abd2.uEdge = edge;
+                        abd2.rc = monitorRect;
+                        const auto hTaskbar =
+                            reinterpret_cast<HWND>(::SHAppBarMessage(ABM_GETAUTOHIDEBAREX, &abd2));
+                        return (hTaskbar != nullptr);
+                    };
+                    top = hasAutohideTaskbar(ABE_TOP);
+                    bottom = hasAutohideTaskbar(ABE_BOTTOM);
+                    left = hasAutohideTaskbar(ABE_LEFT);
+                    right = hasAutohideTaskbar(ABE_RIGHT);
+                } else {
+                    int edge = -1;
+                    APPBARDATA abd2{};
+                    abd2.cbSize = sizeof(abd2);
+                    abd2.hWnd = ::FindWindowW(L"Shell_TrayWnd", nullptr);
+                    HMONITOR windowMonitor = ::MonitorFromWindow(hWnd, MONITOR_DEFAULTTONEAREST);
+                    HMONITOR taskbarMonitor =
+                        ::MonitorFromWindow(abd2.hWnd, MONITOR_DEFAULTTOPRIMARY);
+                    if (taskbarMonitor == windowMonitor) {
+                        ::SHAppBarMessage(ABM_GETTASKBARPOS, &abd2);
+                        edge = int(abd2.uEdge);
+                    }
+                    top = (edge == ABE_TOP);
+                    bottom = (edge == ABE_BOTTOM);
+                    left = (edge == ABE_LEFT);
+                    right = (edge == ABE_RIGHT);
+                }
+                // If there's a taskbar on any side of the monitor, reduce
+                // our size a little bit on that edge.
+                // Note to future code archeologists:
+                // This doesn't seem to work for fullscreen on the primary
+                // display. However, testing a bunch of other apps with
+                // fullscreen modes and an auto-hiding taskbar has
+                // shown that _none_ of them reveal the taskbar from
+                // fullscreen mode. This includes Edge, Firefox, Chrome,
+                // Sublime Text, PowerPoint - none seemed to support this.
+                // This does however work fine for maximized.
+                if (top) {
+                    // Peculiarly, when we're fullscreen,
+                    clientRect->top += kAutoHideTaskBarThickness;
+                } else if (bottom) {
+                    clientRect->bottom -= kAutoHideTaskBarThickness;
+                } else if (left) {
+                    clientRect->left += kAutoHideTaskBarThickness;
+                } else if (right) {
+                    clientRect->right -= kAutoHideTaskBarThickness;
+                }
+            }
+        }
+        // We should call this function only before the function returns.
+        syncPaintEventWithDwm();
+        // By returning WVR_REDRAW we can make the window resizing look
+        // less broken. But we must return 0 if wParam is FALSE, according to Microsoft
+        // Docs.
+        // **IMPORTANT NOTE**:
+        // If you are drawing something manually through D3D in your window, don't
+        // try to return WVR_REDRAW here, otherwise Windows exhibits bugs where
+        // client pixels and child windows are mispositioned by the width/height
+        // of the upper-left non-client area. It's confirmed that this issue exists
+        // from Windows 7 to Windows 10. Not tested on Windows 11 yet. Don't know
+        // whether it exists on Windows XP to Windows Vista or not.
+        *result = wParam ? WVR_REDRAW : FALSE;
+        return true;
+    }
+
+    bool Win32WindowContext::systemMenuHandler(HWND hWnd, UINT message, WPARAM wParam,
+                                               LPARAM lParam, LRESULT *result) {
+        const auto getNativePosFromMouse = [lParam]() -> POINT {
+            return {GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam)};
+        };
+        const auto getNativeGlobalPosFromKeyboard = [hWnd]() -> POINT {
+            const bool maxOrFull = IsMaximized(hWnd) || isFullScreen(hWnd);
+            const quint32 frameSize = getResizeBorderThickness(hWnd);
+            const quint32 horizontalOffset = ((maxOrFull || !isWin10OrGreater()) ? 0 : frameSize);
+            const auto verticalOffset = [hWnd, maxOrFull, frameSize]() -> quint32 {
+                const quint32 titleBarHeight = getTitleBarHeight(hWnd);
+                if (!isWin10OrGreater()) {
+                    return titleBarHeight;
+                }
+                if (isWin11OrGreater()) {
+                    if (maxOrFull) {
+                        return (titleBarHeight + frameSize);
+                    }
+                    return titleBarHeight;
+                }
+                if (maxOrFull) {
+                    return titleBarHeight;
+                }
+                return titleBarHeight - frameSize;
+            }();
+            RECT windowPos{};
+            ::GetWindowRect(hWnd, &windowPos);
+            return {static_cast<LONG>(windowPos.left + horizontalOffset),
+                    static_cast<LONG>(windowPos.top + verticalOffset)};
+        };
+        bool shouldShowSystemMenu = false;
+        bool broughtByKeyboard = false;
+        POINT nativeGlobalPos{};
+        switch (message) {
+            case WM_RBUTTONUP: {
+                const POINT nativeLocalPos = getNativePosFromMouse();
+                const QPoint qtScenePos =
+                    QHighDpi::fromNativeLocalPosition(point2qpoint(nativeLocalPos), m_windowHandle);
+                if (isInTitleBarDraggableArea(qtScenePos)) {
+                    shouldShowSystemMenu = true;
+                    nativeGlobalPos = nativeLocalPos;
+                    ::ClientToScreen(hWnd, &nativeGlobalPos);
+                }
+                break;
+            }
+            case WM_NCRBUTTONUP: {
+                if (wParam == HTCAPTION) {
+                    shouldShowSystemMenu = true;
+                    nativeGlobalPos = getNativePosFromMouse();
+                }
+                break;
+            }
+            case WM_SYSCOMMAND: {
+                const WPARAM filteredWParam = (wParam & 0xFFF0);
+                if ((filteredWParam == SC_KEYMENU) && (lParam == VK_SPACE)) {
+                    shouldShowSystemMenu = true;
+                    broughtByKeyboard = true;
+                    nativeGlobalPos = getNativeGlobalPosFromKeyboard();
+                }
+                break;
+            }
+            case WM_KEYDOWN:
+            case WM_SYSKEYDOWN: {
+                const bool altPressed = ((wParam == VK_MENU) || (::GetKeyState(VK_MENU) < 0));
+                const bool spacePressed = ((wParam == VK_SPACE) || (::GetKeyState(VK_SPACE) < 0));
+                if (altPressed && spacePressed) {
+                    shouldShowSystemMenu = true;
+                    broughtByKeyboard = true;
+                    nativeGlobalPos = getNativeGlobalPosFromKeyboard();
+                }
+                break;
+            }
+            default:
+                break;
+        }
+        if (shouldShowSystemMenu) {
+            showSystemMenu2(hWnd, nativeGlobalPos, broughtByKeyboard,
+                            m_delegate->isHostSizeFixed(m_host));
+            // QPA's internal code will handle system menu events separately, and its
+            // behavior is not what we would want to see because it doesn't know our
+            // window doesn't have any window frame now, so return early here to avoid
+            // entering Qt's own handling logic.
+            *result = FALSE;
+            return true;
+        }
+        return false;
+    }
+
+}

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