Need Partial Postback Guide

Hi all,

I had developed a web base system by using Ajax and ASP.NET. I placed a updatepanel in one of the page.

The updatepanel enclosed a gridview, modalpopupextender, and others controls. Meanwhile, when I clicked on one of the imagebutton embeded in gridview, one of the gridview will popup by using modalpopupextender and whole page will be postback. So it taken a lot of time to load out entire controls. Thus, I was planned to explore the way partially postback the page. Which only modalpopupextender controls to be postback.

I had tried to locate multiple updatepanel into the page either nested or out of the main updatepanel but it doesn't worked and prompt me a error message ("the extender cannot be outside of others extender <-- something like this ).

Anyone here can give me a good reference or guide to resolve my problem ?

Thanks in advance ......