YUI: customizing message browser shows when cancelling window close event

Question

I have a YUI application. Under certain circumstances I want to alert the user before he closes the window. Therefore I capture the window close event and do

onWindowClose: function(e) {
     if (...)
     {
      YAHOO.util.Event.preventDefault(e);
     }
    }

The browser shows a standrd message: "Are you sure you want to navigate away from this page? Press OK to continue, cancel to stay in the current page".

How can I customize the message the browser shows?

Answer 1

Check for onbeforeunload event and my answer in

http://stackoverflow.com/questions/564778/show-a-message-box-when-user-close-ie/564850#564850

and

http://stackoverflow.com/questions/250055/asp-net-warning-on-changed-data-closing-windows

It may work for you.