Sys.UI.DomEvent stopPropagation Method
Prevents an event from being propagated (bubbled) to parent elements.
domEventVar.stopPropagation();
Remarks
By default, event notification is bubbled from a child object to parent objects until it reaches the document object. The event notification stops if the event is handled during the propagation process. Use the stopPropagation method to prevent an event from being propagated to parent elements.