Add ajax spinning gif to a zone.

Hello, I'm wondering how you can add an animated load .gif to my app
letting a user know an ajax request is underway? Example, when you do an
ajax file upload, is thee a way to show the animated gif until the file has
be loaded into the interface? I'm not sure if I can do this with zones nor
do I know how to fire or stop it. Any incite would be greatly appreciated.