Expose BCP47 language id for system locale as property in the shell scripting interface.

shell/scripting/appinterface.cpp

@@ -130,6 +130,11 @@ QString AppInterface::language() const
     return QLocale::system().languageToString(QLocale::system().language());
 }
 
+QString AppInterface::languageId() const
+{
+    return QLocale::system().bcp47Name().section('-', 0, 0);
+}
+
 bool AppInterface::multihead() const
 {
 #ifdef Q_OS_WIN

shell/scripting/appinterface.h

@@ -55,6 +55,7 @@ class AppInterface : public QObject
     Q_PROPERTY(bool multiheadScreen READ multihead)
     Q_PROPERTY(QString locale READ locale)
     Q_PROPERTY(QString language READ language)
+    Q_PROPERTY(QString languageId READ languageId)
 
 public:
     AppInterface(ScriptEngine *env);
@@ -78,6 +79,7 @@ public:
 
     QString locale() const;
     QString language() const;
+    QString languageId() const;
 
     bool multihead() const;
     int multiheadScreen() const;