Your question is not clear to me. You write about an Ajax panel, Ajax UpdateProgress and an event from the page. Ajax is not a product but a sort of setup where HTML, JavaScript and a server script work together asynchronously.
Back to your question: after the request is sent to the server, you can trace the status of your HttpRequest. When the server script is finished, this is indicated in the HttpRequest status. Usually the Ajax function, depending on the package you use, checks the HttpRequest status and sets some sort of completion status at the client side for you to act upon. At that point you can obtain the server results and use it to populate your page.
Now what is it exactly you are looking for?
Ronald :cool: