显示进度条并禁用页面的所有内容，直到页面加载

I have lots of ASP.NET Pages in which all the contents of the page has been placed inside Content Panel on each page..They takes some time to load fully when requested. Now I want to show a GIF image and that Page remains un-editable until it loads Fully using JQuery.. Please don't give examples using div tag as I m dealing with content panel. Any Ideas??I have lots of ASP.NET Pages in which all the c