--- a/svghmi/i18n.py	Tue Feb 16 11:35:56 2021 +0100
+++ b/svghmi/i18n.py	Tue Feb 16 11:47:52 2021 +0100
@@ -64,9 +64,10 @@
         w.write(POT_file)
 
 def ReadTranslations(dirpath):
-    """ Read all PO files from a directory and return a list of (lang, translation_dict) tuples """
+    """ Read all PO files from a directory and return a list of (langcode, translation_dict) tuples """
 
     po_files = [fname for fname in os.listdir(dirpath) if fname.endswith(".po")]
+    po_files.sort()
 
     translations = []
     for po_fname in po_files:
@@ -86,34 +87,35 @@
     broken_lang = set()
     for msgid,label,svgid in messages:
         translated_message = []
-        for lang,translation in translations:
+        for langcode,translation in translations:
             msg = translation.pop(msgid, None)
             if msg is None:
-                broken_lang.add(lang)
+                broken_lang.add(langcode)
                 errcallback(_('{}: Missing translation for "{}" (label:{}, id:{})\n').format(lang,msgid,label,svgid))
                 translated_message.append(msgid)
             else:
                 translated_message.append(msg)
         translated_messages.append((msgid,translated_message))
     langs = []
-    for lang,translation in translations:
+    for langcode,translation in translations:
         try:
-            l,c = lang.split("_")
+            l,c = langcode.split("_")
             language_name = pycountry.languages.get(alpha_2 = l).name
             country_name = pycountry.countries.get(alpha_2 = c).name
-            langs.append("{} ({})".format(language_name, country_name))
+            langname = "{} ({})".format(language_name, country_name)
         except:
             try:
-                language_name = pycountry.languages.get(alpha_2 = lang).name
-                langs.append(language_name)
+                langname = pycountry.languages.get(alpha_2 = langcode).name
             except:
-                langs.append(lang)
+                langname = langcode
+
+        langs.append((langname,langcode))
 
         broken = False
         for msgid, msg in translation.iteritems():
             broken = True
-            errcallback(_('{}: Unused translation "{}":"{}"\n').format(lang,msgid,msg))
-        if broken or lang in broken_lang:
+            errcallback(_('{}: Unused translation "{}":"{}"\n').format(langcode,msgid,msg))
+        if broken or langcode in broken_lang:
             errcallback(_('Translation for {} is outdated, please edit {}.po, click "Catalog -> Update from POT File..." and select messages.pot.\n').format(lang,lang))
 
 
@@ -125,9 +127,9 @@
     result = etree.Element("translations")
 
     langsroot = etree.SubElement(result, "langs")
-    for lang in langs:
-        langel = etree.SubElement(langsroot, "lang")
-        langel.text = lang
+    for name, code in langs:
+        langel = etree.SubElement(langsroot, "lang", {"code":code})
+        langel.text = name
 
     msgsroot = etree.SubElement(result, "messages")
     for msgid, msgs in translated_messages:

--- a/svghmi/i18n.ysl2	Tue Feb 16 11:35:56 2021 +0100
+++ b/svghmi/i18n.ysl2	Tue Feb 16 11:47:52 2021 +0100
@@ -20,9 +20,9 @@
 
 emit "preamble:i18n" {
     const "translations", "ns:GetTranslations($translatable_strings)";
-    > var langs = [ "default",
+    > var langs = [ ["Default", "C"],
     foreach "$translations/langs/lang" {
-        > "«.»"
+        > ["«.»","«@code»"]
         if "position()!=last()" > ,
     }
     | ];

--- a/svghmi/svghmi.js	Tue Feb 16 11:35:56 2021 +0100
+++ b/svghmi/svghmi.js	Tue Feb 16 11:47:52 2021 +0100
@@ -212,37 +212,48 @@
 }
 
 function switch_langnum(langnum) {
-    if(langnum == current_lang) {
-        return;
-    }
+    langnum = Math.max(0, Math.min(langs.length - 1, langnum));
 
     for (let translation of translations) {
-        let [objs, msgs, orig] = translation;
-        let msg = langnum == 0 ? orig : msgs[langnum - 1];
+        let [objs, msgs] = translation;
+        let msg = msgs[langnum];
         for (let obj of objs) {
             multiline_to_svg_text(obj, msg);
             obj.setAttribute("lang",langnum);
         }
     }
-    current_lang = langnum;
+    return langnum;
 }
 
 // backup original texts
 for (let translation of translations) {
-    let [objs] = translation;
-    translation.push(svg_text_to_multiline(objs[0])); 
+    let [objs, msgs] = translation;
+    msgs.unshift(svg_text_to_multiline(objs[0])); 
 }
 
 var lang_local_index = hmi_local_index("lang");
+var langcode_local_index = hmi_local_index("lang_code");
+var langname_local_index = hmi_local_index("lang_name");
 subscribers(lang_local_index).add({
     indexes: [lang_local_index],
     new_hmi_value: function(index, value, oldval) {
-        switch_langnum(value);
+        let current_lang =  switch_langnum(value);
+        let [langname,langcode] = langs[current_lang];
+        apply_hmi_value(langcode_local_index, langcode);
+        apply_hmi_value(langname_local_index, langname);
         switch_page();
     }
 });
-var current_lang = 0;
-switch_langnum(cache[lang_local_index]);
+
+function setup_lang(){
+    let current_lang = cache[lang_local_index];
+    let new_lang = switch_langnum(current_lang);
+    if(current_lang != new_lang){
+        apply_hmi_value(lang_local_index, new_lang);
+    }
+}
+
+setup_lang();
 
 function update_subscriptions() {
     let delta = [];