diff --git a/uppdev/Lang/Lang.upp b/uppdev/Lang/Lang.upp
index c0dfa73d3..b3e5a7965 100644
--- a/uppdev/Lang/Lang.upp
+++ b/uppdev/Lang/Lang.upp
@@ -1,12 +1,14 @@
-uses
-	CtrlLib;
-
-file
-	D:\Core.t charset "UTF-8",
-	D:\CtrlLib.t,
-	main.cpp charset "windows-1250",
-	test.lay,
-	test.t charset "UTF-8";
-
-mainconfig
-	"" = "GUI ST";
+uses
+	CtrlLib;
+
+file
+	D:\Core.t charset "UTF-8",
+	D:\CtrlLib.t,
+	main.cpp charset "windows-1250",
+	test.lay,
+	test.t charset "UTF-8";
+
+mainconfig
+	"" = "GUI ST",
+	"" = "GUI MT";
+
diff --git a/uppdev/Lang/main.cpp b/uppdev/Lang/main.cpp
index b5224a955..8c8523398 100644
--- a/uppdev/Lang/main.cpp
+++ b/uppdev/Lang/main.cpp
@@ -1,12 +1,40 @@
-#include "CtrlLib/CtrlLib.h"
-
-using namespace Upp;
-
-#define   TFILE <Lang/test.t>
-#include  <Core/t.h>
-
-GUI_APP_MAIN
-{
-	DUMP(LNGFromText(String()));
-	DUMP(LNGAsText(GetSystemLNG()));
-}
+#include "CtrlLib/CtrlLib.h"
+
+using namespace Upp;
+
+//#define   TFILE <Lang/test.t>
+//#include  <Core/t.h>
+
+void ThreadTest(int lang)
+{
+	RLOG("In thread0: " << LNGAsText(lang) << ' ' << t_("Invalid date/time:"));
+	RLOG("In thread0: " << LNGAsText(lang) << ' ' << t_("Cancel"));
+	RLOG("In thread0 S: " << LNGAsText(lang) << ' ' << GetLngString("Cancel"));		
+	RLOG("In thread0: " << LNGAsText(lang) << ' ' << AsString(GetSysDate()));
+	SetLanguage(lang);
+	for(int i = 0; i < 10; i++) {
+		Sleep(100);
+		RLOG("In thread: " << LNGAsText(lang) << ' ' << t_("Invalid date/time:"));
+		RLOG("In thread: " << LNGAsText(lang) << ' ' << t_("Cancel"));
+		RLOG("In thread S: " << LNGAsText(lang) << ' ' << GetLngString("Cancel"));		
+		RLOG("In thread: " << LNGAsText(lang) << ' ' << AsString(GetSysDate()));
+	}
+	
+}
+
+GUI_APP_MAIN
+{
+	RDUMP(LNGAsText(GetSystemLNG()));
+	RDUMP(t_("Sunday"));
+	Thread::Start(callback1(ThreadTest, LNG_('P','L','P','L')));
+	Thread::Start(callback1(ThreadTest, LNG_('F','R','F','R')));
+	Thread::Start(callback1(ThreadTest, LNG_ENGLISH));
+	SetLanguage(LNG_('C','S','C','Z'));
+	for(int i = 0; i < 10; i++) {
+		Sleep(100);
+		RLOG("Main: " << t_("Sunday"));
+		RLOG("Main: " << t_("Cancel"));
+		RLOG("Main S: " << GetLngString("Cancel"));		
+		RLOG("Main: " << AsString(GetSysDate()));
+	}
+}