Visit Disney’s toon-town website in Ubuntu (I tried it with Epiphany and Firefox) and you get this:
Yep. It bugs me too. But the game is distributed Windows-only, even though Panda itself is cross-platform, for business reasons. And it makes a certain amount of sense to check the user’s platform at the front door, since there’s not much point in browsing the website if you can’t play the game.
David