Expanding Property

//The client side event Expanding takes two parameters, sender and e.
//Sender is the object which is raising the event
//e is the SplitterPaneExpandedEventArgs
function WebSplitter1_Expanding(sender, e) {
   var websplitter = $find("WebSplitter1);

   // Gets a reference to the pane that is related to the browser event in 
   // the splitter bar
   var websplitterPane = websplitter.getPaneFromEvent(e);

   // Confirm if end user wants to expand the pane
   if (!confirm("Do you want to continue expanding the pane?"))
      e.set_cancel(true);

   // Gets the size of the expanded pane
   var size = websplitterPane.get_size();
   window.status = "Size of expanded pane "+ size;
}