From 9b1599d82e86d2d0463b60fe6fa61f94be50f983 Mon Sep 17 00:00:00 2001
From: Yuhang Zhao <zhaoyuhang@rankyee.com>
Date: 周二, 05 12月 2023 14:48:52 +0800
Subject: [PATCH] port some more code (for os < win10)

---
 src/core/contexts/win32windowcontext.cpp | 1364 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 1,330 insertions(+), 34 deletions(-)

diff --git a/src/core/contexts/win32windowcontext.cpp b/src/core/contexts/win32windowcontext.cpp
index ab32ed0..49a6d69 100644
--- a/src/core/contexts/win32windowcontext.cpp
+++ b/src/core/contexts/win32windowcontext.cpp
@@ -1,16 +1,433 @@
 #include "win32windowcontext_p.h"
 
+#include <optional>
+
 #include <QtCore/QHash>
+#include <QtCore/QAbstractNativeEventFilter>
+#include <QtCore/QCoreApplication>
+#include <QtCore/QOperatingSystemVersion>
+#include <QtCore/QScopeGuard>
+
+#include <QtCore/private/qsystemlibrary_p.h>
+#include <QtGui/private/qhighdpiscaling_p.h>
+
+#include "qwkcoreglobal_p.h"
+
+#include <shellscalingapi.h>
+#include <dwmapi.h>
 
 namespace QWK {
 
+    static constexpr const auto kAutoHideTaskBarThickness =
+        quint8{2}; // The thickness of an auto-hide taskbar in pixels.
+
     using WndProcHash = QHash<HWND, Win32WindowContext *>; // hWnd -> context
-    Q_GLOBAL_STATIC(WndProcHash, g_wndProcHash);
+    Q_GLOBAL_STATIC(WndProcHash, g_wndProcHash)
 
     static WNDPROC g_qtWindowProc = nullptr; // Original Qt window proc function
 
-    extern "C" LRESULT QT_WIN_CALLBACK QWK_WindowsWndProc(HWND hWnd, UINT message, WPARAM wParam,
-                                                          LPARAM lParam) {
+    struct DynamicApis {
+        decltype(&::DwmFlush) pDwmFlush = nullptr;
+        decltype(&::DwmIsCompositionEnabled) pDwmIsCompositionEnabled = nullptr;
+        decltype(&::GetDpiForWindow) pGetDpiForWindow = nullptr;
+        decltype(&::GetSystemMetricsForDpi) pGetSystemMetricsForDpi = nullptr;
+        decltype(&::GetDpiForMonitor) pGetDpiForMonitor = nullptr;
+
+        DynamicApis() {
+            QSystemLibrary user32(QStringLiteral("user32.dll"));
+            pGetDpiForWindow =
+                reinterpret_cast<decltype(pGetDpiForWindow)>(user32.resolve("GetDpiForWindow"));
+            pGetSystemMetricsForDpi = reinterpret_cast<decltype(pGetSystemMetricsForDpi)>(
+                user32.resolve("GetSystemMetricsForDpi"));
+
+            QSystemLibrary shcore(QStringLiteral("shcore.dll"));
+            pGetDpiForMonitor =
+                reinterpret_cast<decltype(pGetDpiForMonitor)>(shcore.resolve("GetDpiForMonitor"));
+
+            QSystemLibrary dwmapi(QStringLiteral("dwmapi.dll"));
+            pDwmFlush = reinterpret_cast<decltype(pDwmFlush)>(dwmapi.resolve("DwmFlush"));
+            pDwmIsCompositionEnabled = reinterpret_cast<decltype(pDwmIsCompositionEnabled)>(dwmapi.resolve("DwmIsCompositionEnabled"));
+        }
+
+        ~DynamicApis() = default;
+
+        static const DynamicApis &instance() {
+            static const DynamicApis inst{};
+            return inst;
+        }
+
+    private:
+        Q_DISABLE_COPY_MOVE(DynamicApis)
+    };
+
+    static inline constexpr bool operator==(const POINT &lhs, const POINT &rhs) noexcept {
+        return ((lhs.x == rhs.x) && (lhs.y == rhs.y));
+    }
+
+    static inline constexpr bool operator!=(const POINT &lhs, const POINT &rhs) noexcept {
+        return !operator==(lhs, rhs);
+    }
+
+    static inline constexpr bool operator==(const SIZE &lhs, const SIZE &rhs) noexcept {
+        return ((lhs.cx == rhs.cx) && (lhs.cy == rhs.cy));
+    }
+
+    static inline constexpr bool operator!=(const SIZE &lhs, const SIZE &rhs) noexcept {
+        return !operator==(lhs, rhs);
+    }
+
+    static inline constexpr bool operator>(const SIZE &lhs, const SIZE &rhs) noexcept {
+        return ((lhs.cx * lhs.cy) > (rhs.cx * rhs.cy));
+    }
+
+    static inline constexpr bool operator>=(const SIZE &lhs, const SIZE &rhs) noexcept {
+        return (operator>(lhs, rhs) || operator==(lhs, rhs));
+    }
+
+    static inline constexpr bool operator<(const SIZE &lhs, const SIZE &rhs) noexcept {
+        return (operator!=(lhs, rhs) && !operator>(lhs, rhs));
+    }
+
+    static inline constexpr bool operator<=(const SIZE &lhs, const SIZE &rhs) noexcept {
+        return (operator<(lhs, rhs) || operator==(lhs, rhs));
+    }
+
+    static inline constexpr bool operator==(const RECT &lhs, const RECT &rhs) noexcept {
+        return ((lhs.left == rhs.left) && (lhs.top == rhs.top) && (lhs.right == rhs.right) &&
+                (lhs.bottom == rhs.bottom));
+    }
+
+    static inline constexpr bool operator!=(const RECT &lhs, const RECT &rhs) noexcept {
+        return !operator==(lhs, rhs);
+    }
+
+    static inline constexpr QPoint point2qpoint(const POINT &point) {
+        return QPoint{int(point.x), int(point.y)};
+    }
+
+    static inline constexpr POINT qpoint2point(const QPoint &point) {
+        return POINT{LONG(point.x()), LONG(point.y())};
+    }
+
+    static inline constexpr QSize size2qsize(const SIZE &size) {
+        return QSize{int(size.cx), int(size.cy)};
+    }
+
+    static inline constexpr SIZE qsize2size(const QSize &size) {
+        return SIZE{LONG(size.width()), LONG(size.height())};
+    }
+
+    static inline constexpr QRect rect2qrect(const RECT &rect) {
+        return QRect{
+            QPoint{int(rect.left),        int(rect.top)         },
+            QSize{int(RECT_WIDTH(rect)), int(RECT_HEIGHT(rect))}
+        };
+    }
+
+    static inline constexpr RECT qrect2rect(const QRect &qrect) {
+        return RECT{LONG(qrect.left()), LONG(qrect.top()), LONG(qrect.right()),
+                    LONG(qrect.bottom())};
+    }
+
+    static inline /*constexpr*/ QString hwnd2str(const WId windowId) {
+        // NULL handle is allowed here.
+        return QLatin1String("0x") +
+               QString::number(windowId, 16).toUpper().rightJustified(8, u'0');
+    }
+
+    static inline /*constexpr*/ QString hwnd2str(HWND hwnd) {
+        // NULL handle is allowed here.
+        return hwnd2str(reinterpret_cast<WId>(hwnd));
+    }
+
+    static inline bool isWin8OrGreater() {
+        static const bool result =
+            QOperatingSystemVersion::current() >= QOperatingSystemVersion::Windows8;
+        return result;
+    }
+
+    static inline bool isWin8Point1OrGreater() {
+        static const bool result =
+            QOperatingSystemVersion::current() >= QOperatingSystemVersion::Windows8_1;
+        return result;
+    }
+
+    static inline bool isWin10OrGreater() {
+        static const bool result =
+            QOperatingSystemVersion::current() >= QOperatingSystemVersion::Windows10;
+        return result;
+    }
+
+    static inline bool isDwmCompositionEnabled() {
+        if (isWin8OrGreater()) {
+            return true;
+        }
+        const DynamicApis &apis = DynamicApis::instance();
+        if (!apis.pDwmIsCompositionEnabled) {
+            return false;
+        }
+        BOOL enabled = FALSE;
+        return SUCCEEDED(apis.pDwmIsCompositionEnabled(&enabled)) && enabled;
+    }
+
+    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 USER_DEFAULT_SCREEN_DPI;
+        }
+        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};
+            apis.pGetDpiForMonitor(monitor, MDT_EFFECTIVE_DPI, &dpiX, &dpiY);
+            return dpiX;
+        } else { // Win2K
+            HDC hdc = ::GetDC(nullptr);
+            const int dpiX = ::GetDeviceCaps(hdc, LOGPIXELSX);
+            const int dpiY = ::GetDeviceCaps(hdc, LOGPIXELSY);
+            ::ReleaseDC(nullptr, hdc);
+            return quint32(dpiX);
+        }
+    }
+
+    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);
+            return apis.pGetSystemMetricsForDpi(SM_CXSIZEFRAME, dpi) +
+                   apis.pGetSystemMetricsForDpi(SM_CXPADDEDBORDER, dpi);
+        } else {
+            return ::GetSystemMetrics(SM_CXSIZEFRAME) + ::GetSystemMetrics(SM_CXPADDEDBORDER);
+        }
+    }
+
+    static inline std::optional<MONITORINFOEXW> getMonitorForWindow(HWND hwnd) {
+        Q_ASSERT(hwnd);
+        if (!hwnd) {
+            return std::nullopt;
+        }
+        // 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);
+        MONITORINFOEXW monitorInfo{};
+        monitorInfo.cbSize = sizeof(monitorInfo);
+        ::GetMonitorInfoW(monitor, &monitorInfo);
+        return monitorInfo;
+    };
+
+    static inline bool isFullScreen(HWND hwnd) {
+        Q_ASSERT(hwnd);
+        if (!hwnd) {
+            return false;
+        }
+        RECT windowRect{};
+        ::GetWindowRect(hwnd, &windowRect);
+        const std::optional<MONITORINFOEXW> mi = getMonitorForWindow(hwnd);
+        // Compare to the full area of the screen, not the work area.
+        return (windowRect == mi.value_or(MONITORINFOEXW{}).rcMonitor);
+    }
+
+    static inline bool isWindowNoState(HWND hwnd) {
+        Q_ASSERT(hwnd);
+        if (!hwnd) {
+            return false;
+        }
+#if 0
+        WINDOWPLACEMENT wp{};
+        wp.length = sizeof(wp);
+        ::GetWindowPlacement(hwnd, &wp);
+        return ((wp.showCmd == SW_NORMAL) || (wp.showCmd == SW_RESTORE));
+#else
+        const auto style = static_cast<DWORD>(::GetWindowLongPtrW(hwnd, GWL_STYLE));
+        return (!(style & (WS_MINIMIZE | WS_MAXIMIZE)));
+#endif
+    }
+
+    static inline QPoint fromNativeLocalPosition(const QWindow *window, const QPoint &point) {
+        Q_ASSERT(window);
+        if (!window) {
+            return point;
+        }
+#if 1
+        return QHighDpi::fromNativeLocalPosition(point, window);
+#else
+        return QPointF(QPointF(point) / window->devicePixelRatio()).toPoint();
+#endif
+    }
+
+    static inline Win32WindowContext::WindowPart getHitWindowPart(int hitTestResult) {
+        switch (hitTestResult) {
+            case HTCLIENT:
+                return Win32WindowContext::ClientArea;
+            case HTCAPTION:
+                return Win32WindowContext::TitleBar;
+            case HTSYSMENU:
+            case HTHELP:
+            case HTREDUCE:
+            case HTZOOM:
+            case HTCLOSE:
+                return Win32WindowContext::ChromeButton;
+            case HTLEFT:
+            case HTRIGHT:
+            case HTTOP:
+            case HTTOPLEFT:
+            case HTTOPRIGHT:
+            case HTBOTTOM:
+            case HTBOTTOMLEFT:
+            case HTBOTTOMRIGHT:
+                return Win32WindowContext::ResizeBorder;
+            case HTBORDER:
+                return Win32WindowContext::FixedBorder;
+            default:
+                break; // unreachable
+        }
+        return Win32WindowContext::Outside;
+    }
+
+    static bool isValidWindow(HWND hWnd, bool checkVisible, bool checkTopLevel) {
+        if (::IsWindow(hWnd) == FALSE) {
+            return false;
+        }
+        const LONG_PTR styles = ::GetWindowLongPtrW(hWnd, GWL_STYLE);
+        if (styles & WS_DISABLED) {
+            return false;
+        }
+        const LONG_PTR exStyles = ::GetWindowLongPtrW(hWnd, GWL_EXSTYLE);
+        if (exStyles & WS_EX_TOOLWINDOW) {
+            return false;
+        }
+        RECT rect = {0, 0, 0, 0};
+        if (::GetWindowRect(hWnd, &rect) == FALSE) {
+            return false;
+        }
+        if ((rect.left >= rect.right) || (rect.top >= rect.bottom)) {
+            return false;
+        }
+        if (checkVisible) {
+            if (::IsWindowVisible(hWnd) == FALSE) {
+                return false;
+            }
+        }
+        if (checkTopLevel) {
+            if (::GetAncestor(hWnd, GA_ROOT) != hWnd) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    // https://github.com/qt/qtbase/blob/e26a87f1ecc40bc8c6aa5b889fce67410a57a702/src/plugins/platforms/windows/qwindowscontext.cpp#L1556
+    // In QWindowsContext::windowsProc(), the messages will be passed to all global native event
+    // filters, but because we have already filtered the messages in the hook WndProc function for
+    // convenience, Qt does not know we may have already processed the messages and thus will call
+    // 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 {
+    public:
+        bool nativeEventFilter(const QByteArray &eventType, void *message,
+                               QT_NATIVE_EVENT_RESULT_TYPE *result) override {
+            // 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;
+            }
+            return false;
+        }
+
+        static bool lastMessageHandled;
+        static LRESULT lastMessageResult;
+        static WindowsNativeEventFilter *instance;
+
+        static inline void install() {
+            instance = new WindowsNativeEventFilter();
+            installNativeEventFilter(instance);
+        }
+
+        static inline void uninstall() {
+            removeNativeEventFilter(instance);
+            delete instance;
+            instance = nullptr;
+        }
+    };
+
+    bool WindowsNativeEventFilter::lastMessageHandled = false;
+    LRESULT WindowsNativeEventFilter::lastMessageResult = 0;
+    WindowsNativeEventFilter *WindowsNativeEventFilter::instance = 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
+    // unfiltered messages to the event dispatcher. To activate the Snap Layout feature on Windows
+    // 11, we must process some non-client area messages ourselves, but unfortunately these messages
+    // have been filtered out already in that line, and thus we'll never have the chance to process
+    // them ourselves. This is Qt's low level platform specific code, so we don't have any official
+    // ways to change this behavior. But luckily we can replace the window procedure function of
+    // Qt's windows, and in this hooked window procedure function, we finally have the chance to
+    // process window messages before Qt touches them. So we reconstruct the MSG structure and send
+    // it to our own custom native event filter to do all the magic works. But since the system menu
+    // feature doesn't necessarily belong to the native implementation, we seperate the handling
+    // code and always process the system menu part in this function for both implementations.
+    //
+    // Original event flow:
+    //      [Entry]             Windows Message Queue
+    //                          |
+    //      [Qt Window Proc]    qwindowscontext.cpp#L1547: qWindowsWndProc()
+    //                              ```
+    //                              const bool handled = QWindowsContext::instance()->windowsProc
+    //                                  (hwnd, message, et, wParam, lParam, &result,
+    //                                  &platformWindow);
+    //                              ```
+    //                          |
+    //      [Non-Input Filter]  qwindowscontext.cpp#L1025: QWindowsContext::windowsProc()
+    //                              ```
+    //                              if (!isInputMessage(msg.message) &&
+    //                                  filterNativeEvent(&msg, result))
+    //                                  return true;
+    //                              ```
+    //                          |
+    //      [User Filter]       qwindowscontext.cpp#L1588: QWindowsContext::windowsProc()
+    //                              ```
+    //                              QAbstractEventDispatcher *dispatcher =
+    //                              QAbstractEventDispatcher::instance();
+    //                              qintptr filterResult = 0;
+    //                              if (dispatcher &&
+    //                              dispatcher->filterNativeEvent(nativeEventType(), msg,
+    //                              &filterResult)) {
+    //                                  *result = LRESULT(filterResult);
+    //                                  return true;
+    //                              }
+    //                              ```
+    //                          |
+    //      [Extra work]        The rest of QWindowsContext::windowsProc() and qWindowsWndProc()
+    //
+    // Notice: Only non-input messages will be processed by the user-defined global native event
+    // filter!!! These events are then passed to the widget class's own overridden
+    // QWidget::nativeEvent() as a local filter, where all native events can be handled, but we must
+    // create a new class derived from QWidget which we don't intend to. Therefore, we don't expect
+    // to process events from the global native event filter, but instead hook Qt's window
+    // procedure.
+
+    extern "C" LRESULT QT_WIN_CALLBACK QWKHookedWndProc(HWND hWnd, UINT message, WPARAM wParam,
+                                                        LPARAM lParam) {
         Q_ASSERT(hWnd);
         if (!hWnd) {
             return FALSE;
@@ -22,55 +439,56 @@
             return ::DefWindowProcW(hWnd, message, wParam, lParam);
         }
 
-        // Try hooked procedure
-        LRESULT result;
-        bool handled = ctx->windowProc(hWnd, message, wParam, lParam, &result);
-        if (handled) {
-            return result;
-        }
+        // Try hooked procedure and save result
+        auto &handled = WindowsNativeEventFilter::lastMessageHandled;
+        auto &result = WindowsNativeEventFilter::lastMessageResult;
+        handled = ctx->windowProc(hWnd, message, wParam, lParam, &result);
 
-        // Fallback to Qt's procedure
+        // TODO: Determine whether to show system menu
+        // ...
+
+        // Since Qt does the necessary processing of the message afterward, we still need to
+        // continue dispatching it.
         return ::CallWindowProcW(g_qtWindowProc, hWnd, message, wParam, lParam);
     }
 
     Win32WindowContext::Win32WindowContext(QWindow *window, WindowItemDelegate *delegate)
-        : AbstractWindowContext(window, delegate), windowId(0) {
+        : AbstractWindowContext(window, delegate) {
     }
 
     Win32WindowContext::~Win32WindowContext() {
         // Remove window handle mapping
-        auto hWnd = reinterpret_cast<HWND>(windowId);
-        g_wndProcHash->remove(hWnd);
+        if (auto hWnd = reinterpret_cast<HWND>(windowId); hWnd) {
+            g_wndProcHash->remove(hWnd);
+
+            // Remove event filter if the all windows has been destroyed
+            if (g_wndProcHash->empty()) {
+                WindowsNativeEventFilter::uninstall();
+            }
+        }
     }
 
     bool Win32WindowContext::setup() {
         auto winId = m_windowHandle->winId();
-        Q_ASSERT(winId);
-        if (!winId) {
-            return false;
-        }
 
         // Install window hook
         auto hWnd = reinterpret_cast<HWND>(winId);
-        auto qtWindowProc = reinterpret_cast<WNDPROC>(::GetWindowLongPtrW(hWnd, GWLP_WNDPROC));
-        Q_ASSERT(qtWindowProc);
-        if (!qtWindowProc) {
-            QWK_WARNING << winLastErrorMessage();
-            return false;
-        }
-
-        if (::SetWindowLongPtrW(hWnd, GWLP_WNDPROC,
-                                reinterpret_cast<LONG_PTR>(QWK_WindowsWndProc)) == 0) {
-            QWK_WARNING << winLastErrorMessage();
-            return false;
-        }
-
-        windowId = winId;
 
         // Store original window proc
         if (!g_qtWindowProc) {
-            g_qtWindowProc = qtWindowProc;
+            g_qtWindowProc = reinterpret_cast<WNDPROC>(::GetWindowLongPtrW(hWnd, GWLP_WNDPROC));
         }
+
+        // Hook window proc
+        ::SetWindowLongPtrW(hWnd, GWLP_WNDPROC, reinterpret_cast<LONG_PTR>(QWKHookedWndProc));
+
+        // Install global native event filter
+        if (!WindowsNativeEventFilter::instance) {
+            WindowsNativeEventFilter::install();
+        }
+
+        // Cache window ID
+        windowId = winId;
 
         // Save window handle mapping
         g_wndProcHash->insert(hWnd, this);
@@ -82,10 +500,888 @@
                                         LRESULT *result) {
         *result = FALSE;
 
-        // TODO: Implement
-        // ...
+        // We should skip these messages otherwise we will get crashes.
+        // NOTE: WM_QUIT won't be posted to the WindowProc function.
+        switch (message) {
+            case WM_CLOSE:
+            case WM_DESTROY:
+            case WM_NCDESTROY:
+            // Undocumented messages:
+            case WM_UAHDESTROYWINDOW:
+            case WM_UNREGISTER_WINDOW_SERVICES:
+                return false;
+            default:
+                break;
+        }
+
+        if (!isValidWindow(hWnd, false, true)) {
+            return false;
+        }
+
+        // Test snap layout
+        if (snapLayoutHandler(hWnd, message, wParam, lParam, result)) {
+            return true;
+        }
+
+        // Main implementation
+        if (customWindowHandler(hWnd, message, wParam, lParam, result)) {
+            return true;
+        }
 
         return false; // Not handled
     }
 
+    static constexpr const auto kMessageTag = WPARAM(0x97CCEA99);
+
+    static inline constexpr bool isTaggedMessage(WPARAM wParam) {
+        return (wParam == kMessageTag);
+    }
+
+    static inline quint64 getKeyState() {
+        quint64 result = 0;
+        const auto &get = [](const int virtualKey) -> bool {
+            return (::GetAsyncKeyState(virtualKey) < 0);
+        };
+        const bool buttonSwapped = (::GetSystemMetrics(SM_SWAPBUTTON) != FALSE);
+        if (get(VK_LBUTTON)) {
+            result |= (buttonSwapped ? MK_RBUTTON : MK_LBUTTON);
+        }
+        if (get(VK_RBUTTON)) {
+            result |= (buttonSwapped ? MK_LBUTTON : MK_RBUTTON);
+        }
+        if (get(VK_SHIFT)) {
+            result |= MK_SHIFT;
+        }
+        if (get(VK_CONTROL)) {
+            result |= MK_CONTROL;
+        }
+        if (get(VK_MBUTTON)) {
+            result |= MK_MBUTTON;
+        }
+        if (get(VK_XBUTTON1)) {
+            result |= MK_XBUTTON1;
+        }
+        if (get(VK_XBUTTON2)) {
+            result |= MK_XBUTTON2;
+        }
+        return result;
+    }
+
+    static void emulateClientAreaMessage(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam,
+                                         const std::optional<int> &overrideMessage = std::nullopt) {
+        const int myMsg = overrideMessage.value_or(message);
+        const auto wParamNew = [myMsg, wParam]() -> WPARAM {
+            if (myMsg == WM_NCMOUSELEAVE) {
+                // wParam is always ignored in mouse leave messages, but here we
+                // give them a special tag to be able to distinguish which messages
+                // are sent by ourselves.
+                return kMessageTag;
+            }
+            const quint64 keyState = getKeyState();
+            if ((myMsg >= WM_NCXBUTTONDOWN) && (myMsg <= WM_NCXBUTTONDBLCLK)) {
+                const auto xButtonMask = GET_XBUTTON_WPARAM(wParam);
+                return MAKEWPARAM(keyState, xButtonMask);
+            }
+            return keyState;
+        }();
+        const auto lParamNew = [myMsg, lParam, hWnd]() -> LPARAM {
+            if (myMsg == WM_NCMOUSELEAVE) {
+                // lParam is always ignored in mouse leave messages.
+                return 0;
+            }
+            const auto screenPos = POINT{GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam)};
+            POINT clientPos = screenPos;
+            ::ScreenToClient(hWnd, &clientPos);
+            return MAKELPARAM(clientPos.x, clientPos.y);
+        }();
+#if 0
+#  define SEND_MESSAGE ::SendMessageW
+#else
+#  define SEND_MESSAGE ::PostMessageW
+#endif
+        switch (myMsg) {
+            case WM_NCHITTEST: // Treat hit test messages as mouse move events.
+            case WM_NCMOUSEMOVE:
+                SEND_MESSAGE(hWnd, WM_MOUSEMOVE, wParamNew, lParamNew);
+                break;
+            case WM_NCLBUTTONDOWN:
+                SEND_MESSAGE(hWnd, WM_LBUTTONDOWN, wParamNew, lParamNew);
+                break;
+            case WM_NCLBUTTONUP:
+                SEND_MESSAGE(hWnd, WM_LBUTTONUP, wParamNew, lParamNew);
+                break;
+            case WM_NCLBUTTONDBLCLK:
+                SEND_MESSAGE(hWnd, WM_LBUTTONDBLCLK, wParamNew, lParamNew);
+                break;
+            case WM_NCRBUTTONDOWN:
+                SEND_MESSAGE(hWnd, WM_RBUTTONDOWN, wParamNew, lParamNew);
+                break;
+            case WM_NCRBUTTONUP:
+                SEND_MESSAGE(hWnd, WM_RBUTTONUP, wParamNew, lParamNew);
+                break;
+            case WM_NCRBUTTONDBLCLK:
+                SEND_MESSAGE(hWnd, WM_RBUTTONDBLCLK, wParamNew, lParamNew);
+                break;
+            case WM_NCMBUTTONDOWN:
+                SEND_MESSAGE(hWnd, WM_MBUTTONDOWN, wParamNew, lParamNew);
+                break;
+            case WM_NCMBUTTONUP:
+                SEND_MESSAGE(hWnd, WM_MBUTTONUP, wParamNew, lParamNew);
+                break;
+            case WM_NCMBUTTONDBLCLK:
+                SEND_MESSAGE(hWnd, WM_MBUTTONDBLCLK, wParamNew, lParamNew);
+                break;
+            case WM_NCXBUTTONDOWN:
+                SEND_MESSAGE(hWnd, WM_XBUTTONDOWN, wParamNew, lParamNew);
+                break;
+            case WM_NCXBUTTONUP:
+                SEND_MESSAGE(hWnd, WM_XBUTTONUP, wParamNew, lParamNew);
+                break;
+            case WM_NCXBUTTONDBLCLK:
+                SEND_MESSAGE(hWnd, WM_XBUTTONDBLCLK, wParamNew, lParamNew);
+                break;
+#if 0 // ### TODO: How to handle touch events?
+        case WM_NCPOINTERUPDATE:
+        case WM_NCPOINTERDOWN:
+        case WM_NCPOINTERUP:
+            break;
+#endif
+            case WM_NCMOUSEHOVER:
+                SEND_MESSAGE(hWnd, WM_MOUSEHOVER, wParamNew, lParamNew);
+                break;
+            case WM_NCMOUSELEAVE:
+                SEND_MESSAGE(hWnd, WM_MOUSELEAVE, wParamNew, lParamNew);
+                break;
+            default:
+                break;
+        }
+
+#undef SEND_MESSAGE
+    }
+
+    static inline void requestForMouseLeaveMessage(HWND hWnd, bool nonClient) {
+        TRACKMOUSEEVENT tme{};
+        tme.cbSize = sizeof(tme);
+        tme.dwFlags = TME_LEAVE;
+        if (nonClient) {
+            tme.dwFlags |= TME_NONCLIENT;
+        }
+        tme.hwndTrack = hWnd;
+        tme.dwHoverTime = HOVER_DEFAULT;
+        ::TrackMouseEvent(&tme);
+    }
+
+    bool Win32WindowContext::snapLayoutHandler(HWND hWnd, UINT message, WPARAM wParam,
+                                               LPARAM lParam, LRESULT *result) {
+        switch (message) {
+            case WM_MOUSELEAVE: {
+                if (!isTaggedMessage(wParam)) {
+                    // Qt will call TrackMouseEvent() to get the WM_MOUSELEAVE message when it
+                    // receives WM_MOUSEMOVE messages, and since we are converting every
+                    // WM_NCMOUSEMOVE message to WM_MOUSEMOVE message and send it back to the window
+                    // to be able to hover our controls, we also get lots of WM_MOUSELEAVE messages
+                    // at the same time because of the reason above, and these superfluous mouse
+                    // leave events cause Qt to think the mouse has left the control, and thus we
+                    // 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;
+                    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()
+                        // again, resulting in the client area not responding to any mouse event.
+                        mouseLeaveBlocked = true;
+                        *result = FALSE;
+                        return true;
+                    }
+                }
+                mouseLeaveBlocked = false;
+                break;
+            }
+
+            case WM_MOUSEMOVE: {
+                // At appropriate time, we will call TrackMouseEvent() for Qt. Simultaneously,
+                // we unset `mouseLeaveBlocked` mark and pretend as if Qt has received
+                // WM_MOUSELEAVE.
+                if (lastHitTestResult != WindowPart::ChromeButton && mouseLeaveBlocked) {
+                    mouseLeaveBlocked = false;
+                    requestForMouseLeaveMessage(hWnd, false);
+                }
+                break;
+            }
+
+            case WM_NCMOUSEMOVE:
+            case WM_NCLBUTTONDOWN:
+            case WM_NCLBUTTONUP:
+            case WM_NCLBUTTONDBLCLK:
+            case WM_NCRBUTTONDOWN:
+            case WM_NCRBUTTONUP:
+            case WM_NCRBUTTONDBLCLK:
+            case WM_NCMBUTTONDOWN:
+            case WM_NCMBUTTONUP:
+            case WM_NCMBUTTONDBLCLK:
+            case WM_NCXBUTTONDOWN:
+            case WM_NCXBUTTONUP:
+            case WM_NCXBUTTONDBLCLK:
+#if 0 // ### TODO: How to handle touch events?
+    case WM_NCPOINTERUPDATE:
+    case WM_NCPOINTERDOWN:
+    case WM_NCPOINTERUP:
+#endif
+            case WM_NCMOUSEHOVER: {
+                const WindowPart currentWindowPart = lastHitTestResult;
+                if (message == WM_NCMOUSEMOVE) {
+                    if (currentWindowPart != WindowPart::ChromeButton) {
+                        std::ignore = m_delegate->resetQtGrabbedControl();
+                        if (mouseLeaveBlocked) {
+                            emulateClientAreaMessage(hWnd, message, wParam, lParam,
+                                                     WM_NCMOUSELEAVE);
+                        }
+                    }
+
+                    // We need to make sure we get the right hit-test result when a WM_NCMOUSELEAVE
+                    // comes, so we reset it when we receive a WM_NCMOUSEMOVE.
+
+                    // If the mouse is entering the client area, there must be a WM_NCHITTEST
+                    // setting it to `Client` before the WM_NCMOUSELEAVE comes; if the mouse is
+                    // leaving the window, current window part remains as `Outside`.
+                    lastHitTestResult = WindowPart::Outside;
+                }
+
+                if (currentWindowPart == WindowPart::ChromeButton) {
+                    emulateClientAreaMessage(hWnd, message, wParam, lParam);
+                    if (message == WM_NCMOUSEMOVE) {
+                        // ### FIXME FIXME FIXME
+                        // ### FIXME: Calling DefWindowProc() here is really dangerous, investigate
+                        // how to avoid doing this.
+                        // ### FIXME FIXME FIXME
+                        *result = ::DefWindowProcW(hWnd, WM_NCMOUSEMOVE, wParam, lParam);
+                    } else {
+                        // According to MSDN, we should return non-zero for X button messages to
+                        // indicate we have handled these messages (due to historical reasons), for
+                        // all other messages we should return zero instead.
+                        *result =
+                            (((message >= WM_NCXBUTTONDOWN) && (message <= WM_NCXBUTTONDBLCLK))
+                                 ? TRUE
+                                 : FALSE);
+                    }
+                    return true;
+                }
+                break;
+            }
+
+            case WM_NCMOUSELEAVE: {
+                const WindowPart currentWindowPart = lastHitTestResult;
+                if (currentWindowPart == WindowPart::ChromeButton) {
+                    // If we press on the chrome button and move mouse, Windows will take the
+                    // pressing area as HTCLIENT which maybe because of our former retransmission of
+                    // WM_NCLBUTTONDOWN, as a result, a WM_NCMOUSELEAVE will come immediately and a
+                    // lot of WM_MOUSEMOVE will come if we move the mouse, we should track the mouse
+                    // in advance.
+                    if (mouseLeaveBlocked) {
+                        mouseLeaveBlocked = false;
+                        requestForMouseLeaveMessage(hWnd, false);
+                    }
+                } else {
+                    if (mouseLeaveBlocked) {
+                        // The mouse is moving from the chrome button to other non-client area, we
+                        // should emulate a WM_MOUSELEAVE message to reset the button state.
+                        emulateClientAreaMessage(hWnd, message, wParam, lParam, WM_NCMOUSELEAVE);
+                    }
+
+                    if (currentWindowPart == WindowPart::Outside) {
+                        // Notice: we're not going to clear window part cache when the mouse leaves
+                        // 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();
+                    }
+                }
+                break;
+            }
+
+            default:
+                break;
+        }
+        return false;
+    }
+
+    bool Win32WindowContext::customWindowHandler(HWND hWnd, UINT message, WPARAM wParam,
+                                                 LPARAM lParam, LRESULT *result) {
+        switch (message) {
+            case WM_NCCALCSIZE: {
+                // 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 == 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;
+                    }
+                }
+                // 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;
+            }
+            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�
+                // 澶栭儴杩涜resize鐨勶紝鍏跺師鐞嗘槸锛學S_THICKFRAME杩欎釜绐楀彛鏍峰紡浼氬湪绐�
+                // 鍙g殑宸︺�佸彸鍜屽簳杈规坊鍔犱笁涓�忔槑鐨剅esize鍖哄煙锛岃繖涓変釜鍖哄煙鍦ㄦ甯哥姸鎬�
+                // 涓嬫槸瀹屽叏涓嶅彲瑙佺殑锛屽畠浠敱DWM璐熻矗缁樺埗鍜屾帶鍒躲�傝繖浜涘尯鍩熺殑瀹藉害绛変簬
+                // (SM_CXSIZEFRAME + SM_CXPADDEDBORDER)锛岄珮搴︾瓑浜�
+                // (SM_CYSIZEFRAME + SM_CXPADDEDBORDER)锛屽湪100%缂╂斁鏃讹紝鍧囩瓑
+                // 浜�8鍍忕礌銆傚畠浠睘浜庣獥鍙e尯鍩熺殑涓�閮ㄥ垎锛屼絾涓嶅睘浜庡鎴峰尯锛岃�屾槸灞炰簬闈炲
+                // 鎴峰尯锛屽洜姝etWindowRect鑾峰彇鐨勫尯鍩熶腑鏄寘鍚繖涓変釜resize鍖哄煙鐨勶紝
+                // 鑰孏etClientRect鑾峰彇鐨勫尯鍩熸槸涓嶅寘鍚畠浠殑銆傚綋鎶�
+                // DWMWA_EXTENDED_FRAME_BOUNDS浣滀负鍙傛暟璋冪敤
+                // DwmGetWindowAttribute鏃讹紝涔熻兘鑾峰彇鍒颁竴涓獥鍙eぇ灏忥紝杩欎釜澶у皬浠�
+                // 浜庡墠闈袱鑰呬箣闂达紝鏆傛椂涓嶇煡閬撹繖涓暟鎹殑鎰忎箟鍙婂叾浣滅敤銆傛垜浠湪
+                // WM_NCCALCSIZE娑堟伅鐨勫鐞嗕腑锛屽凡缁忔妸鏁翠釜绐楀彛閮借缃负瀹㈡埛鍖轰簡锛屼篃
+                // 灏辨槸璇达紝鎴戜滑鐨勭獥鍙e凡缁忔病鏈夐潪瀹㈡埛鍖轰簡锛屽洜姝ら偅涓変釜閫忔槑鐨剅esize鍖�
+                // 鍩燂紝姝ゅ埢涔熷凡缁忔垚涓虹獥鍙e鎴峰尯鐨勪竴閮ㄥ垎浜嗭紝浠庤�屽彉寰椾笉閫忔槑浜嗐�傛墍浠�
+                // 鐜板湪鐨剅esize锛岀湅璧锋潵鍍忔槸鍦ㄧ獥鍙e唴閮╮esize锛屾槸鍥犱负鍘熸湰閫忔槑鐨勫湴鏂�
+                // 鐜板湪鍙樺緱涓嶉�忔槑浜嗭紝瀹為檯涓婏紝鍗曠函浠庤寖鍥翠笂鏉ョ湅锛岀幇鍦ㄦ垜浠瑀esize鐨勫湴鏂癸紝
+                // 灏辨槸鏅�氱獥鍙g殑杈规澶栭儴锛岄偅涓変釜閫忔槑鍖哄煙鐨勮寖鍥淬��
+                // 鍥犳锛屽鏋滄垜浠妸杈规瀹屽叏鍘绘帀锛堝氨鏄垜浠鍦ㄥ仛鐨勪簨鎯咃級锛宺esize灏�
+                // 浼氱湅璧锋潵鏄湪鍐呴儴杩涜锛岃繖涓棶棰橀�氳繃甯歌鏂规硶闈炲父闅句互瑙e喅銆傛垜娴嬭瘯杩�
+                // QQ鍜岄拤閽夌殑绐楀彛锛屽畠浠殑绐楀彛灏辨槸鍦ㄥ閮╮esize锛屼絾瀹為檯涓婂畠浠槸閫氳繃
+                // 鎶婄獥鍙e疄闄呯殑鍐呭锛屽祵鍏ュ埌涓�涓畬鍏ㄩ�忔槑鐨勪絾灏哄瑕佸ぇ涓�鍦堢殑绐楀彛涓疄鐜�
+                // 鐨勶紝铏界劧鐪嬭捣鏉ユ晥鏋滆繕涓嶉敊锛屼絾瀵逛簬姝ら」鐩�岃█锛屼唬鐮佸拰绐楀彛缁撴瀯杩囦簬澶�
+                // 鏉傦紝鍥犳鎴戞病鏈夐噰鐢ㄦ鏂规銆傜劧鑰岋紝瀵逛簬鍏蜂綋鐨勮蒋浠堕」鐩�岃█锛屽叾鍋氭硶涔�
+                // 涓嶅け涓轰竴涓紭绉�鐨勮В鍐虫柟妗堬紝姣曠珶鍏跺湪澶у鏁版潯浠朵笅鐨勮〃鐜伴兘杩樺彲浠ャ��
+                //
+                // 鍜�1.x鐨勫仛娉曚笉鍚岋紝鐜板湪鐨�2.x閫夋嫨浜嗕繚鐣欑獥鍙d笁杈癸紝鍘婚櫎鏁翠釜绐楀彛椤堕儴锛�
+                // 濂藉鏄繚鐣欎簡绯荤粺鐨勫師鐢熻竟妗嗭紝澶栬杈冨ソ锛屼笖涓庣郴缁熺粨鍚堢揣瀵嗭紝鑰屼笖resize
+                // 鐨勮〃鐜颁篃鏈夊緢澶ф敼鍠勶紝缂虹偣鏄渶瑕佽嚜琛岀粯鍒堕《閮ㄨ竟妗嗙嚎銆傚師鏈互涓哄彧鑳藉儚
+                // Windows Terminal閭f牱鍦╓M_PAINT閲屾悶榛戦瓟娉曪紝浣嗗悗鏉ュ彂鐜帮紝鍏跺疄鍙�
+                // 瑕侀鑹茬浉杩戯紝鎴戜滑鑷缁樺埗涓�鏍瑰疄绾夸篃鍑犱箮鑳戒互鍋囦贡鐪燂紝鑰屼笖杩欐牱涔熶笉浼�
+                // 鐮村潖Qt鑷繁鐨勭粯鍒剁郴缁燂紝鑳藉仛鍒颁笉渚濊禆榛戦瓟娉曞氨鑳藉疄鐜板儚Windows Terminal
+                // 閭f牱澶栬鍜屽姛鑳介兘姣旇緝瀹岀編鐨勮嚜瀹氫箟杈规銆�
+
+                // A normal Win32 window can be resized outside of it. Here is the
+                // reason: the WS_THICKFRAME window style will cause a window has three
+                // transparent areas beside the window's left, right and bottom
+                // edge. Their width or height is eight pixels if the window is not
+                // scaled. In most cases, they are totally invisible. It's DWM's
+                // responsibility to draw and control them. They exist to let the
+                // user resize the window, visually outside of it. They are in the
+                // window area, but not the client area, so they are in the
+                // non-client area actually. But we have turned the whole window
+                // area into client area in WM_NCCALCSIZE, so the three transparent
+                // resize areas also become a part of the client area and thus they
+                // become visible. When we resize the window, it looks like we are
+                // resizing inside of it, however, that's because the transparent
+                // resize areas are visible now, we ARE resizing outside of the
+                // window actually. But I don't know how to make them become
+                // transparent again without breaking the frame shadow drawn by DWM.
+                // If you really want to solve it, you can try to embed your window
+                // into a larger transparent window and draw the frame shadow
+                // yourself. As what we have said in WM_NCCALCSIZE, you can only
+                // remove the top area of the window, this will let us be able to
+                // resize outside of the window and don't need much process in this
+                // message, it looks like a perfect plan, however, the top border is
+                // missing due to the whole top area is removed, and it's very hard
+                // to bring it back because we have to use a trick in WM_PAINT
+                // (learned from Windows Terminal), but no matter what we do in
+                // WM_PAINT, it will always break the backing store mechanism of Qt,
+                // so actually we can't do it. And it's very difficult to do such
+                // things in NativeEventFilters as well. What's worse, if we really
+                // do this, the four window borders will become white and they look
+                // horrible in dark mode. This solution only supports Windows 10
+                // because the border width on Win10 is only one pixel, however it's
+                // eight pixels on Windows 7 so preserving the three window borders
+                // looks terrible on old systems.
+                //
+                // Unlike the 1.x code, we choose to preserve the three edges of the
+                // window in 2.x, and get rid of the whole top part of the window.
+                // There are quite some advantages such as the appearance looks much
+                // better and due to we have the original system window frame, our
+                // window can behave just like a normal Win32 window even if we now
+                // doesn't have a title bar at all. Most importantly, the flicker and
+                // jitter during window resizing is totally gone now. The disadvantage
+                // is we have to draw a top frame border ourselves. Previously I thought
+                // we have to do the black magic in WM_PAINT just like what Windows
+                // Terminal does, however, later I found that if we choose a proper
+                // color, our homemade top border can almost have exactly the same
+                // appearance with the system's one.
+
+                [[maybe_unused]] const auto &hitTestRecorder = qScopeGuard([this, result]() {
+                    lastHitTestResult = getHitWindowPart(int(*result)); //
+                });
+
+                POINT nativeGlobalPos{GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam)};
+                POINT nativeLocalPos = nativeGlobalPos;
+                ::ScreenToClient(hWnd, &nativeLocalPos);
+
+                RECT clientRect{0, 0, 0, 0};
+                ::GetClientRect(hWnd, &clientRect);
+                auto clientWidth = RECT_WIDTH(clientRect);
+                auto clientHeight = RECT_HEIGHT(clientRect);
+
+                QPoint qtScenePos = fromNativeLocalPosition(
+                    m_windowHandle, QPoint(nativeLocalPos.x, nativeLocalPos.y));
+
+                bool isFixedSize = /*isWindowFixedSize()*/ false; // ### FIXME
+                bool isTitleBar = isInTitleBarDraggableArea(qtScenePos);
+                bool dontOverrideCursor = false;                  // ### TODO
+
+                CoreWindowAgent::SystemButton sysButtonType = CoreWindowAgent::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.
+                    *result = HTNOWHERE;
+                    // Even if the mouse is inside the chrome button area now, we should still allow
+                    // the user to be able to resize the window with the top or right window border,
+                    // 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;
+                        bool isTop = (nativeLocalPos.y <= kBorderSize);
+                        bool isRight = (nativeLocalPos.x >= (clientWidth - kBorderSize));
+                        if (isTop || 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;
+                                } else {
+                                    *result = HTRIGHT;
+                                }
+                            }
+                        }
+                    }
+                    if (*result == HTNOWHERE) {
+                        // OK, we are now really inside one of the chrome buttons, tell Windows the
+                        // exact role of our button. The Snap Layout feature introduced in Windows
+                        // 11 won't work without this.
+                        switch (sysButtonType) {
+                            case CoreWindowAgent::WindowIcon:
+                                *result = HTSYSMENU;
+                                break;
+                            case CoreWindowAgent::Help:
+                                *result = HTHELP;
+                                break;
+                            case CoreWindowAgent::Minimize:
+                                *result = HTREDUCE;
+                                break;
+                            case CoreWindowAgent::Maximize:
+                                *result = HTZOOM;
+                                break;
+                            case CoreWindowAgent::Close:
+                                *result = HTCLOSE;
+                                break;
+                            case CoreWindowAgent::Unknown:
+                                break;
+                            default:
+                                break; // unreachable
+                        }
+                    }
+                    if (*result == HTNOWHERE) {
+                        // OK, it seems we are not inside the window resize area, nor inside the
+                        // chrome buttons, tell Windows we are in the client area to let Qt handle
+                        // this event.
+                        *result = HTCLIENT;
+                    }
+                    return true;
+                }
+                // OK, we are not inside any chrome buttons, try to find out which part of the
+                // window are we hitting.
+
+                bool max = IsMaximized(hWnd);
+                bool full = isFullScreen(hWnd);
+                int frameSize = getResizeBorderThickness(hWnd);
+                bool isTop = (nativeLocalPos.y < frameSize);
+
+                if (isWin10OrGreater()) {
+                    // This will handle the left, right and bottom parts of the frame
+                    // because we didn't change them.
+                    LRESULT originalHitTestResult = ::DefWindowProcW(hWnd, WM_NCHITTEST, 0, lParam);
+                    if (originalHitTestResult != HTCLIENT) {
+                        // Even if the window is not resizable, we still can't return HTCLIENT here
+                        // because when we enter this code path, it means the mouse cursor is
+                        // outside the window, that is, the three transparent window resize area.
+                        // Returning HTCLIENT will confuse Windows, we can't put our controls there
+                        // anyway.
+                        *result = ((isFixedSize || dontOverrideCursor) ? HTBORDER
+                                                                       : originalHitTestResult);
+                        return true;
+                    }
+                    if (full) {
+                        *result = HTCLIENT;
+                        return true;
+                    }
+                    if (max) {
+                        *result = (isTitleBar ? HTCAPTION : HTCLIENT);
+                        return true;
+                    }
+                    // At this point, we know that the cursor is inside the client area
+                    // so it has to be either the little border at the top of our custom
+                    // title bar or the drag bar. Apparently, it must be the drag bar or
+                    // the little border at the top which the user can use to move or
+                    // resize the window.
+                    if (isTop) {
+                        // Return HTCLIENT instead of HTBORDER here, because the mouse is
+                        // inside our homemade title bar now, return HTCLIENT to let our
+                        // title bar can still capture mouse events.
+                        *result = ((isFixedSize || dontOverrideCursor)
+                                       ? (isTitleBar ? HTCAPTION : HTCLIENT)
+                                       : HTTOP);
+                        return true;
+                    }
+                    if (isTitleBar) {
+                        *result = HTCAPTION;
+                        return true;
+                    }
+                    *result = HTCLIENT;
+                } else {
+                    if (full) {
+                        *result = HTCLIENT;
+                        return true;
+                    }
+                    if (max) {
+                        *result = (isTitleBar ? HTCAPTION : HTCLIENT);
+                        return true;
+                    }
+                    if (!isFixedSize) {
+                        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));
+                        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
+                            // inside our window can still capture mouse events.
+                            *result = (isTitleBar ? HTCAPTION : HTCLIENT);
+                            return true;
+                        }
+                        if (isTop) {
+                            if (isLeft) {
+                                *result = HTTOPLEFT;
+                                return true;
+                            }
+                            if (isRight) {
+                                *result = HTTOPRIGHT;
+                                return true;
+                            }
+                            *result = HTTOP;
+                            return true;
+                        }
+                        if (isBottom) {
+                            if (isLeft) {
+                                *result = HTBOTTOMLEFT;
+                                return true;
+                            }
+                            if (isRight) {
+                                *result = HTBOTTOMRIGHT;
+                                return true;
+                            }
+                            *result = HTBOTTOM;
+                            return true;
+                        }
+                        if (isLeft) {
+                            *result = HTLEFT;
+                            return true;
+                        }
+                        if (isRight) {
+                            *result = HTRIGHT;
+                            return true;
+                        }
+                    }
+                    if (isTitleBar) {
+                        *result = HTCAPTION;
+                        return true;
+                    }
+                    *result = HTCLIENT;
+                }
+                return true;
+            }
+            default:
+                break;
+        }
+        if (!isWin10OrGreater()) {
+            switch (message) {
+                case WM_NCUAHDRAWCAPTION:
+                case WM_NCUAHDRAWFRAME: {
+                    // These undocumented messages are sent to draw themed window
+                    // borders. Block them to prevent drawing borders over the client
+                    // area.
+                    *result = FALSE;
+                    return true;
+                }
+                case WM_NCPAINT: {
+                    // 杈规闃村奖澶勪簬闈炲鎴峰尯鐨勮寖鍥达紝鍥犳濡傛灉鐩存帴闃绘闈炲鎴峰尯鐨勭粯鍒讹紝浼氬鑷磋竟妗嗛槾褰变涪澶�
+
+                    if (!isDwmCompositionEnabled()) {
+                        // Only block WM_NCPAINT when DWM composition is disabled. If
+                        // it's blocked when DWM composition is enabled, the frame
+                        // shadow won't be drawn.
+                        *result = FALSE;
+                        return true;
+                    } else {
+                        break;
+                    }
+                }
+                case WM_NCACTIVATE: {
+                    if (isDwmCompositionEnabled()) {
+                        // DefWindowProc won't repaint the window border if lParam (normally a HRGN)
+                        // is -1. See the following link's "lParam" section:
+                        // https://docs.microsoft.com/en-us/windows/win32/winmsg/wm-ncactivate
+                        // Don't use "*result = 0" here, otherwise the window won't respond to the
+                        // window activation state change.
+                        *result = ::DefWindowProcW(hWnd, WM_NCACTIVATE, wParam, -1);
+                    } else {
+                        if (wParam == FALSE) {
+                            *result = TRUE;
+                        } else {
+                            *result = FALSE;
+                        }
+                    }
+                    return true;
+                }
+                case WM_SETICON:
+                case WM_SETTEXT: {
+                    // Disable painting while these messages are handled to prevent them
+                    // from drawing a window caption over the client area.
+                    const auto oldStyle = static_cast<DWORD>(::GetWindowLongPtrW(hWnd, GWL_STYLE));
+                    // Prevent Windows from drawing the default title bar by temporarily
+                    // toggling the WS_VISIBLE style.
+                    const DWORD newStyle = (oldStyle & ~WS_VISIBLE);
+                    ::SetWindowLongPtrW(hWnd, GWL_STYLE, static_cast<LONG_PTR>(newStyle));
+                    triggerFrameChange(hWnd);
+                    const LRESULT originalResult = ::DefWindowProcW(hWnd, message, wParam, lParam);
+                    ::SetWindowLongPtrW(hWnd, GWL_STYLE, static_cast<LONG_PTR>(oldStyle));
+                    triggerFrameChange(hWnd);
+                    *result = originalResult;
+                    return true;
+                }
+                default:
+                    break;
+            }
+        }
+        return false;
+    }
+
 }
\ No newline at end of file

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