Duplicate elements on page using wf:insert_top / wf:insert_bottom in event(init) about n2o HOT 3 CLOSED

event(init) ->
    User = wf:user(),
    wf:reg(room),
    X = wf:qs(<<"x">>),
    wf:insert_top(history,
        #panel{id=banner, body=
            [#span{id=text, body = wf:f("User ~s logged in. X = ~p", [User,X]) },
             #button{id=logout, body="Logout", postback=logout},
             #br{}]}),
    wf:insert_top(history,"-1-");