Other solution for GTK not changing the locale.

src/ex_cmds2.c

@@ -4159,18 +4159,6 @@ ex_language(eap)
 		    set_helplang_default(mname);
 #endif
 		}
-
-		/* Set $LC_CTYPE, because it overrules $LANG, and
-		 * gtk_set_locale() calls setlocale() again.  gnome_init()
-		 * sets $LC_CTYPE to "en_US" (that's a bug!). */
-		if (what != VIM_LC_MESSAGES)
-		    vim_setenv((char_u *)"LC_CTYPE", name);
-# ifdef FEAT_GUI_GTK
-		/* Let GTK know what locale we're using.  Not sure this is
-		 * really needed... */
-		if (gui.in_use)
-		    (void)gtk_set_locale();
-# endif
 	    }
 
 # ifdef FEAT_EVAL

src/main.c

@@ -377,10 +377,6 @@ main
 	    if (params.evim_mode)
 		mch_exit(1);
 	}
-#  if defined(HAVE_LOCALE_H) || defined(X_LOCALE)
-	/* Re-initialize locale, it may have been altered by gui_init_check() */
-	init_locale();
-#  endif
     }
 # endif
 #endif
@@ -1400,6 +1396,10 @@ init_locale()
 {
     setlocale(LC_ALL, "");
 
+# ifdef FEAT_GUI_GTK
+    /* Tell Gtk not to change our locale settings. */
+    gtk_disable_setlocale();
+# endif
 # if defined(FEAT_FLOAT) && defined(LC_NUMERIC)
     /* Make sure strtod() uses a decimal point, not a comma. */
     setlocale(LC_NUMERIC, "C");

src/window.c

@@ -3775,6 +3775,9 @@ goto_tabpage(n)
 goto_tabpage_tp(tp)
     tabpage_T	*tp;
 {
+    /* Don't repeat a message in another tab page. */
+    set_keep_msg(NULL, 0);
+
     if (tp != curtab && leave_tabpage(tp->tp_curwin->w_buffer) == OK)
     {
 	if (valid_tabpage(tp))