Compatible with Waterfox! This add-on compiles data of all loaded tabs, meaning two things: (1) unloaded tabs won't be searched and (2) it takes a while for the search engine to be ready after restarting the browser. Actually, some times it simply doesn't work, at all. Disabling and re-enabling it helps, some times, but not aways. Also, the search pop-up must be closed before searching for newly open tabs (the add-on will conveniently inform how many tabs will be searched on the pop-up). It has no options whatsoever, what is not really a problem, as it works perfectly out-of-the-box, but could have a few tweaks, like an option to search only on the current window's tabs, whole word/phrase search, regex search, case sensitive search and whatnot. Anyway, it's still an amazing and fundamental tool for anyone with more than a half dozen tabs open.