Without any additional program, or popping up any new menu/window/page, is there a way to configure a Firefox extension or Opera or any add-on program to a browser that will let me surf a web page and get a notice in the status bar (or somewhere innocuous on the screen) that the page is valid html/xhtml (or whatever we should be validating to these days) or not?
I actually like the FF version better, but the Opera version can be found here: Web Developer Toolbar & Menu for Opera 7/8 [nontroppo.org]. It takes a little work to set it up (moreso than the FF extension), but it's useful.
This doesn't answer Clark's question, but there's another menu for Opera that I guess is similar to the one that Bill posted: W3-dev Menu [tobyinkster.co.uk].
As for what Clark answered, I don't know if that would be a good idea? Wouldn't that effect load time and upset the webmaster who has to have all of their pages loaded twice (once for the viewer, once for the validator)?