6 files changed, 148 insertions, 15 deletions
diff --git a/src/gui/platform/windows/qwindowsguieventdispatcher.cpp b/src/gui/platform/windows/qwindowsguieventdispatcher.cpp
index f70655380d..c2f0efe96e 100644
--- a/src/gui/platform/windows/qwindowsguieventdispatcher.cpp
+++ b/src/gui/platform/windows/qwindowsguieventdispatcher.cpp
@@ -197,3 +197,5 @@ const char *QWindowsGuiEventDispatcher::windowsMessageName(UINT msg)
 }
 
 QT_END_NAMESPACE
+
+#include "moc_qwindowsguieventdispatcher_p.cpp"
diff --git a/src/gui/platform/windows/qwindowsmimeconverter.cpp b/src/gui/platform/windows/qwindowsmimeconverter.cpp
index d7998a3eb7..49d524cb99 100644
--- a/src/gui/platform/windows/qwindowsmimeconverter.cpp
+++ b/src/gui/platform/windows/qwindowsmimeconverter.cpp
@@ -25,6 +25,22 @@ QT_BEGIN_NAMESPACE
     conversions between Windows Clipboard and MIME formats, you can convert
     proprietary clipboard formats to MIME formats.
 
+    Construct an instance of your converter implementation after instantiating
+    QGuiApplication:
+
+    \code
+    int main(int argc, char **argv)
+    {
+        QGuiApplication app(argc, argv);
+        JsonMimeConverter jsonConverter;
+    }
+    \endcode
+
+    Destroying the instance will unregister the converter and remove support
+    for the conversion. It is also valid to heap-allocate the converter
+    instance; Qt takes ownership and will delete the converter object during
+    QGuiApplication shut-down.
+
     Qt has predefined support for the following Windows Clipboard formats:
 
     \table
@@ -112,6 +128,8 @@ QT_BEGIN_NAMESPACE
 
     The instance is automatically registered, and will be called to convert data during
     clipboard or drag'n'drop operations.
+
+    Call this constructor after QGuiApplication has been created.
 */
 QWindowsMimeConverter::QWindowsMimeConverter()
 {
diff --git a/src/gui/platform/windows/qwindowsmimeconverter.h b/src/gui/platform/windows/qwindowsmimeconverter.h
index 95722be109..145355fe15 100644
--- a/src/gui/platform/windows/qwindowsmimeconverter.h
+++ b/src/gui/platform/windows/qwindowsmimeconverter.h
@@ -1,4 +1,4 @@
-// Copyright (C) 2020 The Qt Company Ltd.
+// Copyright (C) 2022 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
 #ifndef QWINDOWSMIMECONVERTER_P_H
@@ -20,6 +20,7 @@ class QVariant;
 
 class Q_GUI_EXPORT QWindowsMimeConverter
 {
+    Q_DISABLE_COPY(QWindowsMimeConverter)
 public:
     QWindowsMimeConverter();
     virtual ~QWindowsMimeConverter();
diff --git a/src/gui/platform/windows/qwindowsnativeinterface.cpp b/src/gui/platform/windows/qwindowsnativeinterface.cpp
index 86c6593f5d..44f230e1d3 100644
--- a/src/gui/platform/windows/qwindowsnativeinterface.cpp
+++ b/src/gui/platform/windows/qwindowsnativeinterface.cpp
@@ -89,14 +89,20 @@ QOpenGLContext *QNativeInterface::QWGLContext::fromNative(HGLRC context, HWND wi
 QT_DEFINE_PRIVATE_NATIVE_INTERFACE(QWindowsApplication);
 
 /*!
-    \class QNativeInterface::Private::QWindowsScreen
-    \since 6.5
-    \internal
-    \brief Native interface to QScreen, to be retrieved from QPlatformIntegration.
+    \class QNativeInterface::QWindowsScreen
+    \since 6.7
+    \brief Native interface to a screen.
+
+    Accessed through QScreen::nativeInterface().
     \inmodule QtGui
     \ingroup native-interfaces
+    \ingroup native-interfaces-qscreen
 */
-QT_DEFINE_PRIVATE_NATIVE_INTERFACE(QWindowsScreen);
+/*!
+ * \fn HWMONITOR QNativeInterface::QWindowsScreen::handle() const;
+ * \return The underlying HWMONITOR of the screen.
+ */
+QT_DEFINE_NATIVE_INTERFACE(QWindowsScreen);
 /*!
     \enum QNativeInterface::Private::QWindowsApplication::TouchWindowTouchType
 
@@ -175,15 +181,7 @@ QT_DEFINE_PRIVATE_NATIVE_INTERFACE(QWindowsScreen);
     \value DarkModeStyle        The Windows Vista style will be turned off and
                                 a simple dark style will be used.
 
-    \sa isDarkMode(), setDarkModeHandling()
-*/
-
-/*!
-    \fn bool QNativeInterface::Private::QWindowsApplication::isDarkMode() const = 0
-    \internal
-
-    Returns \c true if Windows 10 is configured to use dark mode for
-    applications.
+    \sa setDarkModeHandling()
 */
 
 /*!
diff --git a/src/gui/platform/windows/qwindowsthemecache.cpp b/src/gui/platform/windows/qwindowsthemecache.cpp
new file mode 100644
index 0000000000..3bb92e67ca
--- /dev/null
+++ b/src/gui/platform/windows/qwindowsthemecache.cpp
@@ -0,0 +1,79 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#include "qwindowsthemecache_p.h"
+#include <QtCore/qdebug.h>
+#include <QtCore/qhash.h>
+
+QT_BEGIN_NAMESPACE
+
+// Theme names matching the QWindowsVistaStylePrivate::Theme enumeration.
+constexpr const wchar_t *themeNames[] = {
+    L"BUTTON",   L"COMBOBOX",   L"EDIT",    L"HEADER",    L"LISTVIEW",
+    L"MENU",     L"PROGRESS",   L"REBAR",   L"SCROLLBAR", L"SPIN",
+    L"TAB",      L"TASKDIALOG", L"TOOLBAR", L"TOOLTIP",   L"TRACKBAR",
+    L"WINDOW",   L"STATUS",     L"TREEVIEW"
+};
+
+typedef std::array<HTHEME, std::size(themeNames)> ThemeArray;
+typedef QHash<HWND, ThemeArray> ThemesCache;
+Q_GLOBAL_STATIC(ThemesCache, themesCache);
+
+QString QWindowsThemeCache::themeName(int theme)
+{
+    return theme >= 0 && theme < int(std::size(themeNames))
+        ? QString::fromWCharArray(themeNames[theme]) : QString();
+}
+
+HTHEME QWindowsThemeCache::createTheme(int theme, HWND hwnd)
+{
+    if (Q_UNLIKELY(theme < 0 || theme >= int(std::size(themeNames)) || !hwnd)) {
+        qWarning("Invalid parameters #%d, %p", theme, hwnd);
+        return nullptr;
+    }
+
+    // Get or create themes array for this window.
+    ThemesCache *cache = themesCache();
+    auto it = cache->find(hwnd);
+    if (it == cache->end())
+        it = cache->insert(hwnd, ThemeArray {});
+
+    // Get or create theme data
+    ThemeArray &themes = *it;
+    if (!themes[theme]) {
+        const wchar_t *name = themeNames[theme];
+        themes[theme] = OpenThemeData(hwnd, name);
+        if (Q_UNLIKELY(!themes[theme]))
+            qErrnoWarning("OpenThemeData() failed for theme %d (%s).",
+                          theme, qPrintable(themeName(theme)));
+    }
+    return themes[theme];
+}
+
+static void clearThemes(ThemeArray &themes)
+{
+    for (auto &theme : themes) {
+        if (theme) {
+            CloseThemeData(theme);
+            theme = nullptr;
+        }
+    }
+}
+
+void QWindowsThemeCache::clearThemeCache(HWND hwnd)
+{
+    ThemesCache *cache = themesCache();
+    auto it = cache->find(hwnd);
+    if (it == cache->end())
+        return;
+    clearThemes(*it);
+}
+
+void QWindowsThemeCache::clearAllThemeCaches()
+{
+    ThemesCache *cache = themesCache();
+    for (auto &themeArray : *cache)
+        clearThemes(themeArray);
+}
+
+QT_END_NAMESPACE
diff --git a/src/gui/platform/windows/qwindowsthemecache_p.h b/src/gui/platform/windows/qwindowsthemecache_p.h
new file mode 100644
index 0000000000..beb724dc5c
--- /dev/null
+++ b/src/gui/platform/windows/qwindowsthemecache_p.h
@@ -0,0 +1,35 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QWINDOWSTHEME_CACHE_P_H
+#define QWINDOWSTHEME_CACHE_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API. It exists purely as an
+// implementation detail. This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "QtGui/private/qtguiglobal_p.h"
+
+#include <QtCore/qt_windows.h>
+#include <uxtheme.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace QWindowsThemeCache
+{
+    Q_GUI_EXPORT QString themeName(int theme);
+    Q_GUI_EXPORT HTHEME createTheme(int theme, HWND hwnd);
+    Q_GUI_EXPORT void clearThemeCache(HWND hwnd);
+    Q_GUI_EXPORT void clearAllThemeCaches();
+}
+
+QT_END_NAMESPACE
+
+#endif // QWINDOWSTHEME_CACHE_P_H