Well, I've just tried adding a shortcut to the desktop, and this has a different icon and opens the page as a normal webpage, so I'm happy! Interestingly, the original shortcut had the correct Anywhere Software logo, the new shortcut has a xenForo icon instead..
I don't think opening as a 'webapp' is useful to the user at all. It's a complete pain to have to reload from the start and search again or navigate to wherever..
Anyway, the problem seems to have gone away.