Is there a way to know tab page is switched in scripts?

[fooyoo]

I'd like to capture the event of "tab switch" in script, seems noteSwitched, activeContextChanged is not working for this case. how to capture some event when I switch the tab? Thanks in advance.

[zadam]

Custom widgets can listen to events, the method handlers need to be called with Event suffix - e.g.:

class WordCountWidget extends api.NoteContextAwareWidget {
     ...

     activeContextChangedEvent() {
    }
}

[fooyoo]

It works perfectly! Thank you Zadam!