diff --git a/src/FluFrameless.cpp b/src/FluFrameless.cpp
index 77273b10..1e9551f2 100644
--- a/src/FluFrameless.cpp
+++ b/src/FluFrameless.cpp
@@ -35,6 +35,19 @@ static inline bool isCompositionEnabled() {
     return false;
 }
 
+static inline void setShadow(HWND hwnd) {
+    const MARGINS shadow = {1, 0, 0, 0};
+    typedef HRESULT (WINAPI *DwmExtendFrameIntoClientAreaPtr)(HWND hWnd, const MARGINS *pMarInset);
+    HMODULE module = LoadLibraryW(L"dwmapi.dll");
+    if (module) {
+        DwmExtendFrameIntoClientAreaPtr dwm_extendframe_into_client_area_;
+        dwm_extendframe_into_client_area_ = reinterpret_cast<DwmExtendFrameIntoClientAreaPtr>(GetProcAddress(module, "DwmExtendFrameIntoClientArea"));
+        if (dwm_extendframe_into_client_area_) {
+            dwm_extendframe_into_client_area_(hwnd, &shadow);
+        }
+    }
+}
+
 #endif
 
 bool containsCursorToItem(QQuickItem *item) {
@@ -92,20 +105,31 @@ void FluFrameless::componentComplete() {
     HWND hwnd = reinterpret_cast<HWND>(window()->winId());
     DWORD style = ::GetWindowLongPtr(hwnd, GWL_STYLE);
     if (_fixSize) {
+#if (QT_VERSION == QT_VERSION_CHECK(6, 5, 3) || QT_VERSION == QT_VERSION_CHECK(6, 6, 0))
         ::SetWindowLongPtr(hwnd, GWL_STYLE, style | WS_THICKFRAME);;
+#else
+        ::SetWindowLongPtr(hwnd, GWL_STYLE, style | WS_THICKFRAME | WS_CAPTION);
+#endif
         for (int i = 0; i <= QGuiApplication::screens().count() - 1; ++i) {
             connect(QGuiApplication::screens().at(i), &QScreen::logicalDotsPerInchChanged, this, [=] {
                 SetWindowPos(hwnd, nullptr, 0, 0, 0, 0, SWP_NOZORDER | SWP_NOOWNERZORDER | SWP_NOMOVE | SWP_FRAMECHANGED);
             });
         }
     } else {
+#if (QT_VERSION == QT_VERSION_CHECK(6, 5, 3) || QT_VERSION == QT_VERSION_CHECK(6, 6, 0))
         ::SetWindowLongPtr(hwnd, GWL_STYLE, style | WS_MAXIMIZEBOX | WS_THICKFRAME);
+#else
+        ::SetWindowLongPtr(hwnd, GWL_STYLE, style | WS_MAXIMIZEBOX | WS_THICKFRAME | WS_CAPTION);
+#endif
     }
     SetWindowPos(hwnd, nullptr, 0, 0, 0, 0, SWP_NOZORDER | SWP_NOOWNERZORDER | SWP_NOMOVE | SWP_NOSIZE | SWP_FRAMECHANGED);
     connect(window(), &QQuickWindow::screenChanged, this, [hwnd] {
         ::SetWindowPos(hwnd, nullptr, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER | SWP_FRAMECHANGED | SWP_NOOWNERZORDER);
         ::RedrawWindow(hwnd, nullptr, nullptr, RDW_INVALIDATE | RDW_UPDATENOW);
     });
+    if (!window()->property("_hideShadow").toBool()) {
+        setShadow(hwnd);
+    }
 #endif
     auto appBarHeight = _appbar->height();
     h = qRound(h + appBarHeight);
@@ -149,30 +173,38 @@ void FluFrameless::componentComplete() {
         }
         return false;
     } else if (uMsg == WM_NCCALCSIZE && wParam == TRUE) {
-        const auto clientRect = ((wParam == FALSE) ? reinterpret_cast<LPRECT>(lParam) : &(reinterpret_cast<LPNCCALCSIZE_PARAMS>(lParam))->rgrc[0]);
+        const auto clientRect = &(reinterpret_cast<LPNCCALCSIZE_PARAMS>(lParam))->rgrc[0];
         const LONG originalTop = clientRect->top;
         const LONG originalLeft = clientRect->left;
-        const LONG originalRight = clientRect->right;
         const LONG originalBottom = clientRect->bottom;
+        const LONG originalRight = clientRect->right;
         const LRESULT hitTestResult = ::DefWindowProcW(hwnd, WM_NCCALCSIZE, wParam, lParam);
         if ((hitTestResult != HTERROR) && (hitTestResult != HTNOWHERE)) {
-            *result = hitTestResult;
+            *result = static_cast<QT_NATIVE_EVENT_RESULT_TYPE>(hitTestResult);
             return true;
         }
-        int offsetSize;
+#if (QT_VERSION == QT_VERSION_CHECK(6, 5, 3) || QT_VERSION == QT_VERSION_CHECK(6, 6, 0))
+        clientRect->top = originalTop;
+        clientRect->bottom = originalBottom;
+        clientRect->left = originalLeft;
+        clientRect->right = originalRight;
+#else
         bool isMaximum = ::IsZoomed(hwnd);
-        if (isMaximum || _isFullScreen()) {
-            offsetSize = 0;
+        if (isMaximum) {
+            auto geometry = window()->screen()->geometry();
+            auto offsetX = qAbs(geometry.left() - originalLeft);
+            auto offsetY = qAbs(geometry.top() - originalTop);
+            clientRect->top = originalTop + offsetY;
+            clientRect->bottom = originalBottom - offsetY;
+            clientRect->left = originalLeft + offsetX;
+            clientRect->right = originalRight - offsetX;
         } else {
-            offsetSize = 1;
+            clientRect->top = originalTop;
+            clientRect->bottom = originalBottom;
+            clientRect->left = originalLeft;
+            clientRect->right = originalRight;
         }
-        if (!isCompositionEnabled()) {
-            offsetSize = 0;
-        }
-        clientRect->top = originalTop + offsetSize;
-        clientRect->bottom = originalBottom - offsetSize;
-        clientRect->left = originalLeft + offsetSize;
-        clientRect->right = originalRight - offsetSize;
+#endif
         _setMaximizeHovered(false);
         *result = WVR_REDRAW;
         return true;
@@ -230,12 +262,21 @@ void FluFrameless::componentComplete() {
         *result = HTCLIENT;
         return true;
     } else if (uMsg == WM_NCPAINT) {
+#if (QT_VERSION == QT_VERSION_CHECK(6, 5, 3) || QT_VERSION == QT_VERSION_CHECK(6, 6, 0))
         *result = FALSE;
         return true;
+#else
+        if (isCompositionEnabled()) {
+            return false;
+        }
+        *result = FALSE;
+        return true;
+#endif
     } else if (uMsg == WM_NCACTIVATE) {
         *result = TRUE;
         return true;
     } else if (uMsg == WM_GETMINMAXINFO) {
+#if (QT_VERSION == QT_VERSION_CHECK(6, 5, 3) || QT_VERSION == QT_VERSION_CHECK(6, 6, 0))
         auto *minmaxInfo = reinterpret_cast<MINMAXINFO *>(lParam);
         auto pixelRatio = window()->devicePixelRatio();
         auto geometry = window()->screen()->availableGeometry();
@@ -245,6 +286,7 @@ void FluFrameless::componentComplete() {
         minmaxInfo->ptMaxPosition.y = rect.top;
         minmaxInfo->ptMaxSize.x = qRound(geometry.width() * pixelRatio);
         minmaxInfo->ptMaxSize.y = qRound(geometry.height() * pixelRatio);
+#endif
         return false;
     } else if (_isWindows11OrGreater && (uMsg == WM_NCLBUTTONDBLCLK || uMsg == WM_NCLBUTTONDOWN)) {
         if (_hitMaximizeButton()) {
diff --git a/src/Qt5/imports/FluentUI/Controls/FluAppBar.qml b/src/Qt5/imports/FluentUI/Controls/FluAppBar.qml
index 74e7fc20..9ec2bb56 100644
--- a/src/Qt5/imports/FluentUI/Controls/FluAppBar.qml
+++ b/src/Qt5/imports/FluentUI/Controls/FluAppBar.qml
@@ -43,12 +43,12 @@ Rectangle{
     property alias layoutStandardbuttons: layout_standard_buttons
     property var maxClickListener : function(){
         if(FluTools.isMacos()){
-            if (d.win.visibility === Window.FullScreen)
+            if (d.win.visibility === Window.FullScreen || d.win.visibility === Window.Maximized)
                 d.win.showNormal()
             else
                 d.win.showFullScreen()
         }else{
-            if (d.win.visibility === Window.Maximized)
+            if (d.win.visibility === Window.Maximized || d.win.visibility === Window.FullScreen)
                 d.win.showNormal()
             else
                 d.win.showMaximized()
@@ -93,7 +93,7 @@ Rectangle{
             }
             return false
         }
-        property bool isRestore: win && Window.Maximized === win.visibility
+        property bool isRestore: win && (Window.Maximized === win.visibility || Window.FullScreen === win.visibility)
         property bool resizable: win && !(win.height === win.maximumHeight && win.height === win.minimumHeight && win.width === win.maximumWidth && win.width === win.minimumWidth)
         function containsPointToItem(point,item){
             var pos = item.mapToGlobal(0,0)