Wow! Rated 5 out of 5 stars
Even if it had been only a "styling-only" add-on, having such a nice page with the application logo (SeaMonkey, in my case) rather than Mozilla's bland XUL page would have been a huge bonus; but on the "Page not in cache" page I noticed a "Search" button which IIRC wasn't present in Mozilla's XUL. I didn't use it (I had a link to the desired page on another tab) but I'll have to find out exactly what it does.
P.S. And the application-specific add-on manager logo is a nice touch. Already too many of my SeaMonkey extensions have descriptions saying “for Firefox” or “for Thunderbird”.