allow user to remove a window from the frameless window list

Signed-off-by: Yuhang Zhao <2546789017@qq.com>

include/FramelessHelper/Core/framelesshelper_qt.h

@@ -42,6 +42,7 @@ public:
     ~FramelessHelperQt() override;
 
     static void addWindow(const Global::SystemParameters &params);
+    static void removeWindow(const WId windowId);
 
 protected:
     Q_NODISCARD bool eventFilter(QObject *object, QEvent *event) override;

include/FramelessHelper/Core/framelesshelper_win.h

@@ -41,6 +41,7 @@ public:
     ~FramelessHelperWin() override;
 
     static void addWindow(const Global::SystemParameters &params);
+    static void removeWindow(const WId windowId);
 
     Q_NODISCARD bool nativeEventFilter(const QByteArray &eventType, void *message, QT_NATIVE_EVENT_RESULT_TYPE *result) override;
 };

include/FramelessHelper/Core/framelessmanager.h

@@ -57,6 +57,7 @@ public:
 
 public Q_SLOTS:
     void addWindow(const Global::SystemParameters &params);
+    void removeWindow(const WId windowId);
 
 Q_SIGNALS:
     void systemThemeChanged();

include/FramelessHelper/Core/private/framelessmanager_p.h

@@ -53,10 +53,13 @@ public:
     Q_NODISCARD Global::WallpaperAspectStyle wallpaperAspectStyle() const;
 
     static void addWindow(const Global::SystemParameters &params);
+    static void removeWindow(const WId windowId);
 
     Q_INVOKABLE void notifySystemThemeHasChangedOrNot();
     Q_INVOKABLE void notifyWallpaperHasChangedOrNot();
 
+    Q_NODISCARD static bool usePureQtImplementation();
+
 private:
     void initialize();
 

include/FramelessHelper/Core/utils.h

@@ -42,10 +42,10 @@ Q_DECLARE_LOGGING_CATEGORY(lcUtilsCommon)
 namespace Utils
 {
 
-[[nodiscard]] FRAMELESSHELPER_CORE_API Qt::CursorShape calculateCursorShape(const QWindow *window,
+[[nodiscard]] FRAMELESSHELPER_CORE_API
-                                                                            const QPoint &pos);
+    Qt::CursorShape calculateCursorShape(const QWindow *window, const QPoint &pos);
-[[nodiscard]] FRAMELESSHELPER_CORE_API Qt::Edges calculateWindowEdges(const QWindow *window,
+[[nodiscard]] FRAMELESSHELPER_CORE_API
-                                                                      const QPoint &pos);
+    Qt::Edges calculateWindowEdges(const QWindow *window, const QPoint &pos);
 FRAMELESSHELPER_CORE_API void startSystemMove(QWindow *window, const QPoint &globalPos);
 FRAMELESSHELPER_CORE_API void startSystemResize(QWindow *window, const Qt::Edges edges, const QPoint &globalPos);
 [[nodiscard]] FRAMELESSHELPER_CORE_API QString getSystemButtonIconCode(const Global::SystemButtonType button);

include/FramelessHelper/Quick/framelessquickhelper.h

@@ -50,7 +50,7 @@ class FRAMELESSHELPER_QUICK_API FramelessQuickHelper : public QQuickItem
     Q_PROPERTY(bool windowFixedSize READ isWindowFixedSize WRITE setWindowFixedSize NOTIFY windowFixedSizeChanged FINAL)
     Q_PROPERTY(bool blurBehindWindowEnabled READ isBlurBehindWindowEnabled WRITE setBlurBehindWindowEnabled NOTIFY blurBehindWindowEnabledChanged FINAL)
     Q_PROPERTY(QQuickWindow* window READ window NOTIFY windowChanged2 FINAL)
-    Q_PROPERTY(bool attached READ isAttached NOTIFY attachedChanged FINAL)
+    Q_PROPERTY(bool extendsContentIntoTitleBar READ isContentExtendedIntoTitleBar WRITE setContentExtendedIntoTitleBar NOTIFY extendsContentIntoTitleBarChanged FINAL)
 
 public:
     explicit FramelessQuickHelper(QQuickItem *parent = nullptr);
@@ -62,10 +62,11 @@ public:
     Q_NODISCARD QQuickItem *titleBarItem() const;
     Q_NODISCARD bool isWindowFixedSize() const;
     Q_NODISCARD bool isBlurBehindWindowEnabled() const;
-    Q_NODISCARD bool isAttached() const;
+    Q_NODISCARD bool isContentExtendedIntoTitleBar() const;
 
 public Q_SLOTS:
-    void extendsContentIntoTitleBar();
+    [[deprecated("Use the extendsContentIntoTitleBar property instead.")]] void extendsContentIntoTitleBar();
+    void setContentExtendedIntoTitleBar(const bool value);
 
     void setTitleBarItem(QQuickItem *value);
     void setSystemButton(QQuickItem *item, const QuickGlobal::SystemButtonType buttonType);
@@ -85,11 +86,11 @@ protected:
     void itemChange(const ItemChange change, const ItemChangeData &value) override;
 
 Q_SIGNALS:
+    void extendsContentIntoTitleBarChanged();
     void titleBarItemChanged();
     void windowFixedSizeChanged();
     void blurBehindWindowEnabledChanged();
     void windowChanged2();
-    void attachedChanged();
     void ready();
 
 private:

include/FramelessHelper/Quick/private/framelessquickhelper_p.h

@@ -50,10 +50,14 @@ public:
     Q_NODISCARD static FramelessQuickHelperPrivate *get(FramelessQuickHelper *pub);
     Q_NODISCARD static const FramelessQuickHelperPrivate *get(const FramelessQuickHelper *pub);
 
+    Q_NODISCARD bool isContentExtendedIntoTitleBar() const;
+    void setContentExtendedIntoTitleBar(const bool value);
+
     Q_NODISCARD QQuickItem *getTitleBarItem() const;
     void setTitleBarItem(QQuickItem *value);
 
-    void attachToWindow();
+    void attach();
+    void detach();
     void setSystemButton(QQuickItem *item, const QuickGlobal::SystemButtonType buttonType);
     void setHitTestVisible(QQuickItem *item, const bool visible = true);
     void setHitTestVisible(const QRect &rect, const bool visible = true);
@@ -75,8 +79,6 @@ public:
     void setProperty(const QByteArray &name, const QVariant &value);
     Q_NODISCARD QVariant getProperty(const QByteArray &name, const QVariant &defaultValue = {});
 
-    Q_NODISCARD bool isAttached() const;
-
 protected:
     Q_NODISCARD bool eventFilter(QObject *object, QEvent *event) override;
 

include/FramelessHelper/Widgets/framelesswidgetshelper.h

@@ -44,7 +44,7 @@ class FRAMELESSHELPER_WIDGETS_API FramelessWidgetsHelper : public QObject
     Q_PROPERTY(bool windowFixedSize READ isWindowFixedSize WRITE setWindowFixedSize NOTIFY windowFixedSizeChanged FINAL)
     Q_PROPERTY(bool blurBehindWindowEnabled READ isBlurBehindWindowEnabled WRITE setBlurBehindWindowEnabled NOTIFY blurBehindWindowEnabledChanged FINAL)
     Q_PROPERTY(QWidget* window READ window NOTIFY windowChanged FINAL)
-    Q_PROPERTY(bool attached READ isAttached NOTIFY attachedChanged FINAL)
+    Q_PROPERTY(bool extendsContentIntoTitleBar READ isContentExtendedIntoTitleBar WRITE setContentExtendedIntoTitleBar NOTIFY extendsContentIntoTitleBarChanged FINAL)
 
 public:
     explicit FramelessWidgetsHelper(QObject *parent = nullptr);
@@ -56,10 +56,11 @@ public:
     Q_NODISCARD bool isWindowFixedSize() const;
     Q_NODISCARD bool isBlurBehindWindowEnabled() const;
     Q_NODISCARD QWidget *window() const;
-    Q_NODISCARD bool isAttached() const;
+    Q_NODISCARD bool isContentExtendedIntoTitleBar() const;
 
 public Q_SLOTS:
-    void extendsContentIntoTitleBar();
+    [[deprecated("Use the extendsContentIntoTitleBar property instead.")]] void extendsContentIntoTitleBar();
+    void setContentExtendedIntoTitleBar(const bool value);
 
     void setTitleBarWidget(QWidget *widget);
     void setSystemButton(QWidget *widget, const Global::SystemButtonType buttonType);
@@ -76,11 +77,11 @@ public Q_SLOTS:
     void setBlurBehindWindowEnabled(const bool value);
 
 Q_SIGNALS:
+    void extendsContentIntoTitleBarChanged();
     void titleBarWidgetChanged();
     void windowFixedSizeChanged();
     void blurBehindWindowEnabledChanged();
     void windowChanged();
-    void attachedChanged();
     void ready();
 
 private:

include/FramelessHelper/Widgets/private/framelesswidgetshelper_p.h

@@ -46,10 +46,14 @@ public:
     Q_NODISCARD static FramelessWidgetsHelperPrivate *get(FramelessWidgetsHelper *pub);
     Q_NODISCARD static const FramelessWidgetsHelperPrivate *get(const FramelessWidgetsHelper *pub);
 
+    Q_NODISCARD bool isContentExtendedIntoTitleBar() const;
+    void setContentExtendedIntoTitleBar(const bool value);
+
     Q_NODISCARD QWidget *getTitleBarWidget() const;
     void setTitleBarWidget(QWidget *widget);
 
-    void attachToWindow();
+    void attach();
+    void detach();
     void setSystemButton(QWidget *widget, const Global::SystemButtonType buttonType);
     void setHitTestVisible(QWidget *widget, const bool visible = true);
     void setHitTestVisible(const QRect &rect, const bool visible = true);
@@ -72,7 +76,6 @@ public:
     Q_NODISCARD QVariant getProperty(const QByteArray &name, const QVariant &defaultValue = {});
 
     Q_NODISCARD QWidget *window() const;
-    Q_NODISCARD bool isAttached() const;
 
 private:
     Q_NODISCARD QRect mapWidgetGeometryToScene(const QWidget * const widget) const;

src/core/framelesshelper_qt.cpp

@@ -106,6 +106,24 @@ void FramelessHelperQt::addWindow(const SystemParameters &params)
     FramelessHelper::Core::setApplicationOSThemeAware();
 }
 
+void FramelessHelperQt::removeWindow(const WId windowId)
+{
+    Q_ASSERT(windowId);
+    if (!windowId) {
+        return;
+    }
+    const QMutexLocker locker(&g_qtHelper()->mutex);
+    if (!g_qtHelper()->data.contains(windowId)) {
+        return;
+    }
+    const QtHelperData data = g_qtHelper()->data.value(windowId);
+    g_qtHelper()->data.remove(windowId);
+    if (QWindow * const window = Utils::findWindow(windowId)) {
+        window->removeEventFilter(data.eventFilter);
+    }
+    delete data.eventFilter;
+}
+
 bool FramelessHelperQt::eventFilter(QObject *object, QEvent *event)
 {
     Q_ASSERT(object);

src/core/framelesshelper_win.cpp

@@ -552,6 +552,41 @@ void FramelessHelperWin::addWindow(const SystemParameters &params)
     }
 }
 
+void FramelessHelperWin::removeWindow(const WId windowId)
+{
+    Q_ASSERT(windowId);
+    if (!windowId) {
+        return;
+    }
+    g_win32Helper()->mutex.lock();
+    if (!g_win32Helper()->data.contains(windowId)) {
+        g_win32Helper()->mutex.unlock();
+        return;
+    }
+    g_win32Helper()->data.remove(windowId);
+    if (g_win32Helper()->data.isEmpty()) {
+        if (!g_win32Helper()->nativeEventFilter.isNull()) {
+            qApp->removeNativeEventFilter(g_win32Helper()->nativeEventFilter.data());
+            g_win32Helper()->nativeEventFilter.reset();
+        }
+    }
+    HWND hwnd = nullptr;
+    auto it = g_win32Helper()->fallbackTitleBarToParentWindowMapping.constBegin();
+    while (it != g_win32Helper()->fallbackTitleBarToParentWindowMapping.constEnd()) {
+        if (it.value() == windowId) {
+            const WId key = it.key();
+            hwnd = reinterpret_cast<HWND>(key);
+            g_win32Helper()->fallbackTitleBarToParentWindowMapping.remove(key);
+            break;
+        }
+        ++it;
+    }
+    g_win32Helper()->mutex.unlock();
+    if (DestroyWindow(reinterpret_cast<HWND>(hwnd)) == FALSE) {
+        WARNING << Utils::getSystemErrorMessage(kDestroyWindow);
+    }
+}
+
 bool FramelessHelperWin::nativeEventFilter(const QByteArray &eventType, void *message, QT_NATIVE_EVENT_RESULT_TYPE *result)
 {
     if ((eventType != kWin32MessageTypeName) || !message || !result) {

src/core/framelessmanager.cpp

@@ -54,10 +54,15 @@ Q_LOGGING_CATEGORY(lcFramelessManager, "wangwenx190.framelesshelper.core.framele
 
 using namespace Global;
 
+struct FramelessManagerHelperData
+{
+    QMetaObject::Connection screenChangeConnection = {};
+};
+
 struct FramelessManagerHelper
 {
     QMutex mutex;
-    QList<WId> windowIds = {};
+    QHash<WId, FramelessManagerHelperData> data = {};
 };
 
 Q_GLOBAL_STATIC(FramelessManagerHelper, g_helper)
@@ -182,35 +187,35 @@ void FramelessManagerPrivate::addWindow(const SystemParameters &params)
     }
     const WId windowId = params.getWindowId();
     g_helper()->mutex.lock();
-    if (g_helper()->windowIds.contains(windowId)) {
+    if (g_helper()->data.contains(windowId)) {
         g_helper()->mutex.unlock();
         return;
     }
-    g_helper()->windowIds.append(windowId);
+    g_helper()->data.insert(windowId, {});
     g_helper()->mutex.unlock();
-    static const bool pureQt = []() -> bool {
+    QMetaObject::Connection screenChangeConnection = {};
-#ifdef Q_OS_WINDOWS
+    static const bool pureQt = usePureQtImplementation();
-        return FramelessConfig::instance()->isSet(Option::UseCrossPlatformQtImplementation);
-#else
-        return true;
-#endif
-    }();
 #ifdef Q_OS_WINDOWS
     if (!pureQt) {
         // Work-around Win32 multi-monitor artifacts.
         QWindow * const window = params.getWindowHandle();
         Q_ASSERT(window);
-        connect(window, &QWindow::screenChanged, window, [windowId, window](QScreen *screen){
+        if (window) {
-            Q_UNUSED(screen);
+            g_helper()->mutex.lock();
-            // Force a WM_NCCALCSIZE event to inform Windows about our custom window frame,
+            g_helper()->data[windowId].screenChangeConnection =
-            // this is only necessary when the window is being moved cross monitors.
+                connect(window, &QWindow::screenChanged, window, [windowId, window](QScreen *screen){
-            Utils::triggerFrameChange(windowId);
+                Q_UNUSED(screen);
-            // For some reason the window is not repainted correctly when moving cross monitors,
+                // Force a WM_NCCALCSIZE event to inform Windows about our custom window frame,
-            // we workaround this issue by force a re-paint and re-layout of the window by triggering
+                // this is only necessary when the window is being moved cross monitors.
-            // a resize event manually. Although the actual size does not change, the issue we
+                Utils::triggerFrameChange(windowId);
-            // observed disappeared indeed, amazingly.
+                // For some reason the window is not repainted correctly when moving cross monitors,
-            window->resize(window->size());
+                // we workaround this issue by force a re-paint and re-layout of the window by triggering
-        });
+                // a resize event manually. Although the actual size does not change, the issue we
+                // observed disappeared indeed, amazingly.
+                window->resize(window->size());
+            });
+            g_helper()->mutex.unlock();
+        }
     }
 #endif
     if (pureQt) {
@@ -225,6 +230,37 @@ void FramelessManagerPrivate::addWindow(const SystemParameters &params)
 #endif
 }
 
+void FramelessManagerPrivate::removeWindow(const WId windowId)
+{
+    Q_ASSERT(windowId);
+    if (!windowId) {
+        return;
+    }
+    g_helper()->mutex.lock();
+    if (!g_helper()->data.contains(windowId)) {
+        g_helper()->mutex.unlock();
+        return;
+    }
+    const FramelessManagerHelperData data = g_helper()->data.value(windowId);
+    g_helper()->data.remove(windowId);
+    g_helper()->mutex.unlock();
+    static const bool pureQt = usePureQtImplementation();
+#ifdef Q_OS_WINDOWS
+    if (!pureQt && data.screenChangeConnection) {
+        disconnect(data.screenChangeConnection);
+    }
+#endif
+    if (pureQt) {
+        FramelessHelperQt::removeWindow(windowId);
+    }
+#ifdef Q_OS_WINDOWS
+    if (!pureQt) {
+        FramelessHelperWin::removeWindow(windowId);
+    }
+    Utils::uninstallSystemMenuHook(windowId);
+#endif
+}
+
 void FramelessManagerPrivate::notifySystemThemeHasChangedOrNot()
 {
     const QMutexLocker locker(&g_helper()->mutex);
@@ -282,6 +318,18 @@ void FramelessManagerPrivate::notifyWallpaperHasChangedOrNot()
     }
 }
 
+bool FramelessManagerPrivate::usePureQtImplementation()
+{
+    static const bool result = []() -> bool {
+#ifdef Q_OS_WINDOWS
+        return FramelessConfig::instance()->isSet(Option::UseCrossPlatformQtImplementation);
+#else
+        return true;
+#endif
+    }();
+    return result;
+}
+
 void FramelessManagerPrivate::initialize()
 {
     const QMutexLocker locker(&g_helper()->mutex);
@@ -342,4 +390,10 @@ void FramelessManager::addWindow(const SystemParameters &params)
     d->addWindow(params);
 }
 
+void FramelessManager::removeWindow(const WId windowId)
+{
+    Q_D(FramelessManager);
+    d->removeWindow(windowId);
+}
+
 FRAMELESSHELPER_END_NAMESPACE

src/core/utils_win.cpp

@@ -1154,46 +1154,56 @@ void Utils::fixupQtInternals(const WId windowId)
     if (qEnvironmentVariableIntValue(kNoFixQtInternalEnvVar)) {
         return;
     }
+    bool shouldUpdateFrame = false;
     const auto hwnd = reinterpret_cast<HWND>(windowId);
     SetLastError(ERROR_SUCCESS);
-    const auto oldClassStyle = static_cast<DWORD>(GetClassLongPtrW(hwnd, GCL_STYLE));
+    const auto classStyle = static_cast<DWORD>(GetClassLongPtrW(hwnd, GCL_STYLE));
-    if (oldClassStyle == 0) {
+    if (classStyle != 0) {
+        // CS_HREDRAW/CS_VREDRAW will trigger a repaint event when the window size changes
+        // horizontally/vertically, which will cause flicker and jitter during window resizing,
+        // mostly for the applications which do all the painting by themselves (eg: Qt).
+        // So we remove these flags from the window class here. Qt by default won't add them
+        // but let's make it extra safe in case the user may add them by accident.
+        static constexpr const DWORD badClassStyle = (CS_HREDRAW | CS_VREDRAW);
+        if (classStyle & badClassStyle) {
+            SetLastError(ERROR_SUCCESS);
+            if (SetClassLongPtrW(hwnd, GCL_STYLE,
+                static_cast<LONG_PTR>(classStyle & ~badClassStyle)) == 0) {
+                WARNING << getSystemErrorMessage(kSetClassLongPtrW);
+            } else {
+                shouldUpdateFrame = true;
+            }
+        }
+    } else {
         WARNING << getSystemErrorMessage(kGetClassLongPtrW);
-        return;
-    }
-    // CS_HREDRAW/CS_VREDRAW will trigger a repaint event when the window size changes
-    // horizontally/vertically, which will cause flicker and jitter during window
-    // resizing, mostly for the applications which do all the painting by themselves.
-    // So we remove these flags from the window class here, Qt by default won't add them
-    // but let's make it extra safe.
-    const DWORD newClassStyle = (oldClassStyle & ~(CS_HREDRAW | CS_VREDRAW));
-    SetLastError(ERROR_SUCCESS);
-    if (SetClassLongPtrW(hwnd, GCL_STYLE, static_cast<LONG_PTR>(newClassStyle)) == 0) {
-        WARNING << getSystemErrorMessage(kSetClassLongPtrW);
-        return;
     }
     SetLastError(ERROR_SUCCESS);
-    const auto oldWindowStyle = static_cast<DWORD>(GetWindowLongPtrW(hwnd, GWL_STYLE));
+    const auto windowStyle = static_cast<DWORD>(GetWindowLongPtrW(hwnd, GWL_STYLE));
-    if (oldWindowStyle == 0) {
+    if (windowStyle != 0) {
+        // Qt by default adds the "WS_POPUP" flag to all Win32 windows it created and maintained,
+        // which is not a good thing (although it won't cause any obvious issues in most cases
+        // either), because popup windows have some different behavior with normal overlapped
+        // windows, for example, it will affect DWM's default policy. And Qt will also lack some
+        // necessary window styles in some cases (caused by misconfigured setWindowFlag(s) calls)
+        // and this will also break the normal functionalities for our windows, so we do the
+        // correction here unconditionally.
+        static constexpr const DWORD goodWindowStyle =
+            (WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_THICKFRAME);
+        if (!(windowStyle & goodWindowStyle)) {
+            SetLastError(ERROR_SUCCESS);
+            if (SetWindowLongPtrW(hwnd, GWL_STYLE,
+                static_cast<LONG_PTR>((windowStyle & ~WS_POPUP) | goodWindowStyle)) == 0) {
+                WARNING << getSystemErrorMessage(kSetWindowLongPtrW);
+            } else {
+                shouldUpdateFrame = true;
+            }
+        }
+    } else {
         WARNING << getSystemErrorMessage(kGetWindowLongPtrW);
-        return;
     }
-    // Qt by default adds the "WS_POPUP" flag to all Win32 windows it created and maintained,
+    if (shouldUpdateFrame) {
-    // which is not a good thing (although it won't cause any obvious issues in most cases
+        triggerFrameChange(windowId);
-    // either), because popup windows have some different behavior with normal overlapped
-    // windows, for example, it will affect DWM's default policy. And Qt will also lack some
-    // necessary window styles in some cases (caused by misconfigured setWindowFlag(s) calls)
-    // and this will also break the normal functionalities for our windows, so we do the
-    // correction here unconditionally.
-    static constexpr const DWORD normalWindowStyle =
-        (WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_THICKFRAME);
-    const DWORD newWindowStyle = ((oldWindowStyle & ~WS_POPUP) | normalWindowStyle);
-    SetLastError(ERROR_SUCCESS);
-    if (SetWindowLongPtrW(hwnd, GWL_STYLE, static_cast<LONG_PTR>(newWindowStyle)) == 0) {
-        WARNING << getSystemErrorMessage(kSetWindowLongPtrW);
-        return;
     }
-    triggerFrameChange(windowId);
 }
 
 void Utils::startSystemMove(QWindow *window, const QPoint &globalPos)

src/quick/framelessquickhelper.cpp

@@ -52,7 +52,7 @@ using namespace Global;
 
 struct QuickHelperData
 {
-    bool attached = false;
+    bool ready = false;
     SystemParameters params = {};
     QPointer<QQuickItem> titleBarItem = nullptr;
     QList<QPointer<QQuickItem>> hitTestVisibleItems = {};
@@ -97,11 +97,14 @@ FramelessQuickHelperPrivate::FramelessQuickHelperPrivate(FramelessQuickHelper *q
         return;
     }
     q_ptr = q;
-    // Workaround a moc limitation.
+    // Workaround a MOC limitation: we can't emit a signal from the parent class.
     connect(q_ptr, &FramelessQuickHelper::windowChanged, q_ptr, &FramelessQuickHelper::windowChanged2);
 }
 
-FramelessQuickHelperPrivate::~FramelessQuickHelperPrivate() = default;
+FramelessQuickHelperPrivate::~FramelessQuickHelperPrivate()
+{
+    detach();
+}
 
 FramelessQuickHelperPrivate *FramelessQuickHelperPrivate::get(FramelessQuickHelper *pub)
 {
@@ -121,6 +124,24 @@ const FramelessQuickHelperPrivate *FramelessQuickHelperPrivate::get(const Framel
     return pub->d_func();
 }
 
+bool FramelessQuickHelperPrivate::isContentExtendedIntoTitleBar() const
+{
+    return getWindowData().ready;
+}
+
+void FramelessQuickHelperPrivate::setContentExtendedIntoTitleBar(const bool value)
+{
+    if (isContentExtendedIntoTitleBar() == value) {
+        return;
+    }
+    if (value) {
+        attach();
+    } else {
+        detach();
+    }
+    emitSignalForAllInstances(FRAMELESSHELPER_BYTEARRAY_LITERAL("extendsContentIntoTitleBarChanged"));
+}
+
 QQuickItem *FramelessQuickHelperPrivate::getTitleBarItem() const
 {
     return getWindowData().titleBarItem;
@@ -144,7 +165,7 @@ void FramelessQuickHelperPrivate::setTitleBarItem(QQuickItem *value)
     emitSignalForAllInstances(FRAMELESSHELPER_BYTEARRAY_LITERAL("titleBarItemChanged"));
 }
 
-void FramelessQuickHelperPrivate::attachToWindow()
+void FramelessQuickHelperPrivate::attach()
 {
     Q_Q(FramelessQuickHelper);
     QQuickWindow * const window = q->window();
@@ -154,18 +175,13 @@ void FramelessQuickHelperPrivate::attachToWindow()
     }
 
     g_quickHelper()->mutex.lock();
-    QuickHelperData *data = getWindowDataMutable();
+    QuickHelperData * const data = getWindowDataMutable();
-    if (!data) {
+    if (!data || data->ready) {
         g_quickHelper()->mutex.unlock();
         return;
     }
-    const bool attached = data->attached;
     g_quickHelper()->mutex.unlock();
 
-    if (attached) {
-        return;
-    }
-
     window->installEventFilter(this);
 
     SystemParameters params = {};
@@ -208,7 +224,7 @@ void FramelessQuickHelperPrivate::attachToWindow()
 
     g_quickHelper()->mutex.lock();
     data->params = params;
-    data->attached = true;
+    data->ready = true;
     g_quickHelper()->mutex.unlock();
 
     // We have to wait for a little time before moving the top level window
@@ -223,11 +239,27 @@ void FramelessQuickHelperPrivate::attachToWindow()
         if (FramelessConfig::instance()->isSet(Option::EnableBlurBehindWindow)) {
             setBlurBehindWindowEnabled(true, {});
         }
-        emitSignalForAllInstances(FRAMELESSHELPER_BYTEARRAY_LITERAL("attachedChanged"));
         emitSignalForAllInstances(FRAMELESSHELPER_BYTEARRAY_LITERAL("ready"));
     });
 }
 
+void FramelessQuickHelperPrivate::detach()
+{
+    Q_Q(FramelessQuickHelper);
+    QQuickWindow * const w = q->window();
+    if (!w) {
+        return;
+    }
+    const WId windowId = w->winId();
+    const QMutexLocker locker(&g_quickHelper()->mutex);
+    if (!g_quickHelper()->data.contains(windowId)) {
+        return;
+    }
+    g_quickHelper()->data.remove(windowId);
+    w->removeEventFilter(this);
+    FramelessManager::instance()->removeWindow(windowId);
+}
+
 void FramelessQuickHelperPrivate::setSystemButton(QQuickItem *item, const QuickGlobal::SystemButtonType buttonType)
 {
     Q_ASSERT(item);
@@ -512,12 +544,6 @@ QVariant FramelessQuickHelperPrivate::getProperty(const QByteArray &name, const
     return (value.isValid() ? value : defaultValue);
 }
 
-bool FramelessQuickHelperPrivate::isAttached() const
-{
-    const QMutexLocker locker(&g_quickHelper()->mutex);
-    return getWindowData().attached;
-}
-
 bool FramelessQuickHelperPrivate::eventFilter(QObject *object, QEvent *event)
 {
     Q_ASSERT(object);
@@ -838,7 +864,7 @@ FramelessQuickHelper *FramelessQuickHelper::get(QObject *object)
         instance->setParentItem(parentItem);
         instance->setParent(parent);
         // No need to do this here, we'll do it once the item has been assigned to a specific window.
-        //instance->d_func()->attachToWindow();
+        //instance->d_func()->attach();
     }
     return instance;
 }
@@ -870,15 +896,21 @@ bool FramelessQuickHelper::isBlurBehindWindowEnabled() const
     return d->isBlurBehindWindowEnabled();
 }
 
-bool FramelessQuickHelper::isAttached() const
+bool FramelessQuickHelper::isContentExtendedIntoTitleBar() const
 {
     Q_D(const FramelessQuickHelper);
-    return d->isAttached();
+    return d->isContentExtendedIntoTitleBar();
 }
 
 void FramelessQuickHelper::extendsContentIntoTitleBar()
 {
-    // Intentionally not doing anything here.
+    setContentExtendedIntoTitleBar(true);
+}
+
+void FramelessQuickHelper::setContentExtendedIntoTitleBar(const bool value)
+{
+    Q_D(FramelessQuickHelper);
+    d->setContentExtendedIntoTitleBar(value);
 }
 
 void FramelessQuickHelper::setTitleBarItem(QQuickItem *value)
@@ -988,7 +1020,7 @@ void FramelessQuickHelper::itemChange(const ItemChange change, const ItemChangeD
             }
         }
         Q_D(FramelessQuickHelper);
-        d->attachToWindow();
+        d->attach();
     }
 }
 

src/quick/framelessquickwindow.cpp

@@ -162,7 +162,7 @@ void FramelessQuickWindowPrivate::initialize()
 {
     Q_Q(FramelessQuickWindow);
     QQuickItem * const rootItem = q->contentItem();
-    FramelessQuickHelper::get(rootItem)->extendsContentIntoTitleBar();
+    FramelessQuickHelper::get(rootItem)->setContentExtendedIntoTitleBar(true);
     m_topBorderRectangle.reset(new QQuickRectangle(rootItem));
     m_topBorderRectangle->setZ(999); // Make sure the frame border stays on top of eveything.
     m_topBorderRectangle->setColor(kDefaultTransparentColor);

src/widgets/framelessdialog.cpp

@@ -71,7 +71,7 @@ const FramelessDialogPrivate *FramelessDialogPrivate::get(const FramelessDialog
 void FramelessDialogPrivate::initialize()
 {
     Q_Q(FramelessDialog);
-    FramelessWidgetsHelper::get(q)->extendsContentIntoTitleBar();
+    FramelessWidgetsHelper::get(q)->setContentExtendedIntoTitleBar(true);
     m_helper.reset(new WidgetsSharedHelper(this));
     m_helper->setup(q);
 }

src/widgets/framelessmainwindow.cpp

@@ -71,7 +71,7 @@ const FramelessMainWindowPrivate *FramelessMainWindowPrivate::get(const Frameles
 void FramelessMainWindowPrivate::initialize()
 {
     Q_Q(FramelessMainWindow);
-    FramelessWidgetsHelper::get(q)->extendsContentIntoTitleBar();
+    FramelessWidgetsHelper::get(q)->setContentExtendedIntoTitleBar(true);
     m_helper.reset(new WidgetsSharedHelper(this));
     m_helper->setup(q);
 }

src/widgets/framelesswidget.cpp

@@ -71,7 +71,7 @@ const FramelessWidgetPrivate *FramelessWidgetPrivate::get(const FramelessWidget
 void FramelessWidgetPrivate::initialize()
 {
     Q_Q(FramelessWidget);
-    FramelessWidgetsHelper::get(q)->extendsContentIntoTitleBar();
+    FramelessWidgetsHelper::get(q)->setContentExtendedIntoTitleBar(true);
     m_helper.reset(new WidgetsSharedHelper(this));
     m_helper->setup(q);
 }

src/widgets/framelesswidgetshelper.cpp

@@ -54,7 +54,7 @@ using namespace Global;
 
 struct WidgetsHelperData
 {
-    bool attached = false;
+    bool ready = false;
     SystemParameters params = {};
     QPointer<QWidget> titleBarWidget = nullptr;
     QList<QPointer<QWidget>> hitTestVisibleWidgets = {};
@@ -107,7 +107,10 @@ FramelessWidgetsHelperPrivate::FramelessWidgetsHelperPrivate(FramelessWidgetsHel
     q_ptr = q;
 }
 
-FramelessWidgetsHelperPrivate::~FramelessWidgetsHelperPrivate() = default;
+FramelessWidgetsHelperPrivate::~FramelessWidgetsHelperPrivate()
+{
+    detach();
+}
 
 FramelessWidgetsHelperPrivate *FramelessWidgetsHelperPrivate::get(FramelessWidgetsHelper *pub)
 {
@@ -264,10 +267,9 @@ QWidget *FramelessWidgetsHelperPrivate::window() const
     return m_window;
 }
 
-bool FramelessWidgetsHelperPrivate::isAttached() const
+bool FramelessWidgetsHelperPrivate::isContentExtendedIntoTitleBar() const
 {
-    const QMutexLocker locker(&g_widgetsHelper()->mutex);
+    return getWindowData().ready;
-    return getWindowData().attached;
 }
 
 void FramelessWidgetsHelperPrivate::setTitleBarWidget(QWidget *widget)
@@ -333,7 +335,7 @@ void FramelessWidgetsHelperPrivate::setHitTestVisible(const QRect &rect, const b
     }
 }
 
-void FramelessWidgetsHelperPrivate::attachToWindow()
+void FramelessWidgetsHelperPrivate::attach()
 {
     QWidget * const window = findTopLevelWindow();
     Q_ASSERT(window);
@@ -346,18 +348,13 @@ void FramelessWidgetsHelperPrivate::attachToWindow()
     m_window = window;
 
     g_widgetsHelper()->mutex.lock();
-    WidgetsHelperData *data = getWindowDataMutable();
+    WidgetsHelperData * const data = getWindowDataMutable();
-    if (!data) {
+    if (!data || data->ready) {
         g_widgetsHelper()->mutex.unlock();
         return;
     }
-    const bool attached = data->attached;
     g_widgetsHelper()->mutex.unlock();
 
-    if (attached) {
-        return;
-    }
-
     // Without this flag, Qt will always create an invisible native parent window
     // for any native widgets which will intercept some win32 messages and confuse
     // our own native event filter, so to prevent some weired bugs from happening,
@@ -405,7 +402,7 @@ void FramelessWidgetsHelperPrivate::attachToWindow()
 
     g_widgetsHelper()->mutex.lock();
     data->params = params;
-    data->attached = true;
+    data->ready = true;
     g_widgetsHelper()->mutex.unlock();
 
     // We have to wait for a little time before moving the top level window
@@ -421,11 +418,39 @@ void FramelessWidgetsHelperPrivate::attachToWindow()
             setBlurBehindWindowEnabled(true, {});
         }
         emitSignalForAllInstances(FRAMELESSHELPER_BYTEARRAY_LITERAL("windowChanged"));
-        emitSignalForAllInstances(FRAMELESSHELPER_BYTEARRAY_LITERAL("attachedChanged"));
         emitSignalForAllInstances(FRAMELESSHELPER_BYTEARRAY_LITERAL("ready"));
     });
 }
 
+void FramelessWidgetsHelperPrivate::detach()
+{
+    if (!m_window) {
+        return;
+    }
+    const WId windowId = m_window->winId();
+    const QMutexLocker locker(&g_widgetsHelper()->mutex);
+    if (!g_widgetsHelper()->data.contains(windowId)) {
+        return;
+    }
+    g_widgetsHelper()->data.remove(windowId);
+    FramelessManager::instance()->removeWindow(windowId);
+    m_window = nullptr;
+    emitSignalForAllInstances(FRAMELESSHELPER_BYTEARRAY_LITERAL("windowChanged"));
+}
+
+void FramelessWidgetsHelperPrivate::setContentExtendedIntoTitleBar(const bool value)
+{
+    if (isContentExtendedIntoTitleBar() == value) {
+        return;
+    }
+    if (value) {
+        attach();
+    } else {
+        detach();
+    }
+    emitSignalForAllInstances(FRAMELESSHELPER_BYTEARRAY_LITERAL("extendsContentIntoTitleBarChanged"));
+}
+
 QWidget *FramelessWidgetsHelperPrivate::findTopLevelWindow() const
 {
     Q_Q(const FramelessWidgetsHelper);
@@ -796,7 +821,7 @@ FramelessWidgetsHelper *FramelessWidgetsHelper::get(QObject *object)
     FramelessWidgetsHelper *instance = parent->findChild<FramelessWidgetsHelper *>();
     if (!instance) {
         instance = new FramelessWidgetsHelper(parent);
-        instance->d_func()->attachToWindow();
+        instance->d_func()->attach();
     }
     return instance;
 }
@@ -825,15 +850,21 @@ QWidget *FramelessWidgetsHelper::window() const
     return d->window();
 }
 
-bool FramelessWidgetsHelper::isAttached() const
+bool FramelessWidgetsHelper::isContentExtendedIntoTitleBar() const
 {
     Q_D(const FramelessWidgetsHelper);
-    return d->isAttached();
+    return d->isContentExtendedIntoTitleBar();
 }
 
 void FramelessWidgetsHelper::extendsContentIntoTitleBar()
 {
-    // Intentionally not doing anything here.
+    setContentExtendedIntoTitleBar(true);
+}
+
+void FramelessWidgetsHelper::setContentExtendedIntoTitleBar(const bool value)
+{
+    Q_D(FramelessWidgetsHelper);
+    d->setContentExtendedIntoTitleBar(value);
 }
 
 void FramelessWidgetsHelper::setTitleBarWidget(QWidget *widget)