fix set target in buttons

src/alarm-manager.cpp

@@ -221,7 +221,7 @@ void Alarmmanager::m_tag_written(QObject *writer) {
             const QString &tgtd = ma.capturedTexts()[1];
             printf("current dev is %s target dev is %s\n", qstoc(dev), qstoc(tgtd));
         }
-        if(ma.capturedTexts().size() == 2 && ma.capturedTexts()[1] != dev) {
+        if(t.isEmpty() || (ma.capturedTexts().size() == 2 && ma.capturedTexts()[1] != dev)) {
             t = dev + "->" + b->property("cmd").toString();
             printf("\e[1;31msetting target on button %s: %s\e[0m\n", qstoc(b->objectName()), qstoc(t));
             b->setTarget(t);