IndicatorHide プロパティ

// The client event IndicatorHide takes two parameters sender and e
// sender  is the object which is raising the event
// e is the TabItemEventArgs

function WebTab1_IndicatorHide(sender, e) {

    //Gets the index of the tab involved in the event
    var tabIndex = e.get_tabIndex();

    //Assuming you have a label called labelOutput on the form
    var label = $get('labelOutput');


   label.innerHTML = "Inidcator hidden for tab with index '" + tabIndex + "' ...";            

}