@qjia7 , I'm not sure how you test the secondary display on Tizen? On Android, we do. I'm very appropriated the below code is trying to grab all displays started on system. But I'm not sure how you test your code.

Does Tizen has same feature(secondary display)? If answer is NO, I'd prefer not implement onconnect and ondisconnect event on Tizen, as well as only one display will be reported.