Do not check account availability at each character being typed by the user...

Do not check account availability at each character being typed by the user but only when it's been 500ms since he has not typed anything in.

gtk/setupwizard.c

@@ -283,6 +283,16 @@ void* check_username_availability(void* w) {
 	return NULL;
 }
 
+static gboolean start_check_username_availability_thread(GtkWidget *w) {
+#if !GLIB_CHECK_VERSION(2, 31, 0)
+	g_thread_create(check_username_availability, (void*)w, FALSE, NULL);
+#else
+	g_thread_new(NULL, check_username_availability, w);
+#endif
+	g_object_set_data(G_OBJECT(w), "usernameAvailabilityTimerID", GUINT_TO_POINTER(0));
+	return FALSE;
+}
+
 static void account_username_changed(GtkEntry *entry, GtkWidget *w) {
 	// Verifying if username choosed is available, and if form is correctly filled, let the user go next page
 	GtkWidget *assistant = gtk_widget_get_toplevel(GTK_WIDGET(w));
@@ -295,11 +305,12 @@ static void account_username_changed(GtkEntry *entry, GtkWidget *w) {
 	linphone_account_creator_set_domain(creator, "sip.linphone.org");
 
 	if (g_regex_match_simple("^[a-zA-Z]+[a-zA-Z0-9.\\-_]{3,}$", gtk_entry_get_text(username), 0, 0)) {
-#if !GLIB_CHECK_VERSION(2, 31, 0)
-		g_thread_create(check_username_availability, (void*)w, FALSE, NULL);
-#else
-		g_thread_new(NULL, check_username_availability, w);
-#endif
+		guint timerID = GPOINTER_TO_UINT(g_object_get_data(G_OBJECT(w), "usernameAvailabilityTimerID"));
+		if (timerID > 0) {
+			g_source_remove(timerID);
+		}
+		timerID = g_timeout_add(500, start_check_username_availability_thread, w);
+		g_object_set_data(G_OBJECT(w), "usernameAvailabilityTimerID", GUINT_TO_POINTER(timerID));
 	}
 	else {
 		GdkPixbuf *notok = GDK_PIXBUF(g_object_get_data(G_OBJECT(the_assistant), "notok"));