Me.WebTab1.ClientEvents.TabAdded = "WebTab1_TabAdded"
this.WebTab1.ClientEvents.TabAdded = "WebTab1_TabAdded";
// The client event TabAdded takes two parameters sender and e // sender is the object which is raising the event // e is the TabItemPostBackEventArgs function WebTab1_TabAdded(sender, e) { //Gets the index where a new tab is going to be added var tabIndex = e.get_tabIndex(); //Assuming you have a label called labelOutput on the form var label = $get('labelOutput'); label.innerHTML = "New tab added at index '" + tabIndex + "'!"; }