The ALT tag for images is NOT supposed to produce a little tooltip when you mouseover an image, according to the HTML spec. This is supposed to be the job of the TITLE tag.
Firefox has never done this for ALT tags, correctly obeying the spec. This always confused me, because some images would pop a tooltip and others wouldn’t. Apparently the ones that did also had a TITLE tag, unbeknowst to me.
However, IE has always done it for the ALT tag too, which actually seems reasonable to me. I don’t see the harm.
So someone created an extention for Firefox to “fix” this problem. Not everyone was pleased:
It’s a shame people are producing extensions like this. ALT is the text that is to replace the image if for whatever reason the image doesn’t load. The tooltip text is supposed to be the value of the TITLE attribute.
It’s a shame people are #*X?@ing about the availability of plugins that allow me to view pages in the way I see fit. It’s not as if the mozilla team is forcing you to view pages a certain way and I’ll be damned if I can’t view pages the way I want, regardless of how you code them. If you are blind, can not load images or are saddened by the weakening of the w3c’s role in developing web standards then do not download this plugin.