QMO quality.mozilla.org (alpha)

Hi
Here i have one question on Alt text.

Which i am using application for testing can browse browsers IE and Mozilla Firefox . Alt text and pop message's are not displaying in Firefox 2.0 and 3.0 which is displaying same (pop up msg's and alt text) in IE browsers.
Why Alt text and pop message's not displaying in Firefox browsers?

Any comments please on this issue.