Fix theme detection on Windows 10

Fixes: #8244

Author: TheOneRing

src/common/utility_win.cpp

@@ -45,6 +45,11 @@ const QString runPathC() {
     return QStringLiteral("HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Run");
 }
 
+const QString systemThemesC()
+{
+    return QStringLiteral("HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize");
+}
+
 const QString rtHelperNameC()
 {
     return QStringLiteral(APPLICATION_EXECUTABLE "_winrt");
@@ -138,6 +143,11 @@ void setLaunchOnStartup_private(const QString &appName, const QString &guiName,
 
 static inline bool hasDarkSystray_private()
 {
+    const QString lightThemeKey = QStringLiteral("SystemUsesLightTheme");
+    const QSettings settings(systemThemesC(), QSettings::NativeFormat);
+    if (settings.contains(lightThemeKey)) {
+        return !settings.value(lightThemeKey).toBool();
+    }
     static auto func = funcLoadHelper<bool()>(rtHelperNameC(), "hasDarkSystray");
     return func ? (*func)() : false;
 }