Backport changes to v5.0.x branch

PR #21679.

src/base/preferences.cpp

@@ -429,6 +429,19 @@ void Preferences::setWinStartup(const bool b)
         settings.remove(profileID);
     }
 }
+
+QString Preferences::getStyle() const
+{
+    return value<QString>(u"Appearance/Style"_s);
+}
+
+void Preferences::setStyle(const QString &styleName)
+{
+    if (styleName == getStyle())
+        return;
+
+    setValue(u"Appearance/Style"_s, styleName);
+}
 #endif // Q_OS_WIN
 
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