Comment 2 for bug 671695

https://launchpad.net/wallpaper-changer is not packaged in Ubuntu. All software packaged in Ubuntu is patched to add menu items that link to Launchpad help pages. So the link you are pointing to is not to the firefox project, but to the Ubuntu firefox package.

The Firefox project does not use Answers: https://answers.launchpad.net/firefox
The Ubuntu project doe use Answers: https://answers.launchpad.net/ubuntu/+source/firefox