How to display and remove a loading .gif when downloading a file?

Question

I have a button that, when clicked on, needs to download a file by submitting a form using POST. [Edit to clarify: The file being downloaded is dynamically

Answer 1

I've posted an answer in this question that demonstrates how to do this. See the demo at http://tomsfreelance.com/stackoverflow/imageDownloadLoading/main.php and source files at http://tomsfreelance.com/stackoverflow/imageDownloadLoading/